diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index a04f6b1c86..64cd8ddfc8 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -88,15 +88,28 @@ pub trait BeaconChainTypes {
     type EthSpec: types::EthSpec;
 }
 
+/// Represents the "Beacon Chain" component of Ethereum 2.0. Allows import of blocks and block
+/// operations and chooses a canonical head.
 pub struct BeaconChain<T: BeaconChainTypes> {
+    /// Persistent storage for blocks, states, etc. Typically an on-disk store, such as LevelDB.
     pub store: Arc<T::Store>,
+    /// Reports the current slot, typically based upon the system clock.
     pub slot_clock: T::SlotClock,
+    /// Stores all operations (e.g., `Attestation`, `Deposit`, etc) that are candidates for
+    /// inclusion in a block.
     pub op_pool: OperationPool<T::EthSpec>,
+    /// Stores a "snapshot" of the chain at the time the head-of-the-chain block was recieved.
     canonical_head: RwLock<CheckPoint<T::EthSpec>>,
-    finalized_head: RwLock<CheckPoint<T::EthSpec>>,
+    /// The same state from `self.canonical_head`, but updated at the start of each slot with a
+    /// skip slot if no block is recieved. This is effectively a cache that avoids repeating calls
+    /// to `per_slot_processing`.
     state: RwLock<BeaconState<T::EthSpec>>,
-    pub spec: ChainSpec,
+    /// The root of the genesis block.
+    genesis_block_root: Hash256,
+    /// A state-machine that is updated with information from the network and chooses a canonical
+    /// head block.
     pub fork_choice: RwLock<T::ForkChoice>,
+    /// Stores metrics about this `BeaconChain`.
     pub metrics: Metrics,
 }
 
@@ -113,18 +126,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let state_root = genesis_state.canonical_root();
         store.put(&state_root, &genesis_state)?;
 
-        let block_root = genesis_block.block_header().canonical_root();
-        store.put(&block_root, &genesis_block)?;
+        let genesis_block_root = genesis_block.block_header().canonical_root();
+        store.put(&genesis_block_root, &genesis_block)?;
 
-        let finalized_head = RwLock::new(CheckPoint::new(
-            genesis_block.clone(),
-            block_root,
-            genesis_state.clone(),
-            state_root,
-        ));
         let canonical_head = RwLock::new(CheckPoint::new(
             genesis_block.clone(),
-            block_root,
+            genesis_block_root,
             genesis_state.clone(),
             state_root,
         ));
@@ -136,9 +143,8 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             slot_clock,
             op_pool: OperationPool::new(),
             state: RwLock::new(genesis_state),
-            finalized_head,
             canonical_head,
-            spec,
+            genesis_block_root,
             fork_choice: RwLock::new(fork_choice),
             metrics: Metrics::new()?,
         })
@@ -168,10 +174,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             slot_clock,
             op_pool: OperationPool::default(),
             canonical_head: RwLock::new(p.canonical_head),
-            finalized_head: RwLock::new(p.finalized_head),
             state: RwLock::new(p.state),
-            spec,
             fork_choice: RwLock::new(fork_choice),
+            genesis_block_root: p.genesis_block_root,
             metrics: Metrics::new()?,
         }))
     }
@@ -180,7 +185,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn persist(&self) -> Result<(), Error> {
         let p: PersistedBeaconChain<T> = PersistedBeaconChain {
             canonical_head: self.canonical_head.read().clone(),
-            finalized_head: self.finalized_head.read().clone(),
+            genesis_block_root: self.genesis_block_root,
             state: self.state.read().clone(),
         };
 
@@ -309,42 +314,38 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         Ok(self.store.get(block_root)?)
     }
 
-    /// Update the canonical head to some new values.
-    fn update_canonical_head(
-        &self,
-        new_beacon_block: BeaconBlock,
-        new_beacon_block_root: Hash256,
-        new_beacon_state: BeaconState<T::EthSpec>,
-        new_beacon_state_root: Hash256,
-    ) {
-        debug!(
-            "Updating canonical head with block at slot: {}",
-            new_beacon_block.slot
-        );
-        let mut head = self.canonical_head.write();
-        head.update(
-            new_beacon_block,
-            new_beacon_block_root,
-            new_beacon_state,
-            new_beacon_state_root,
-        );
-    }
-
-    /// Returns a read-lock guarded `CheckPoint` struct for reading the head (as chosen by the
-    /// fork-choice rule).
-    ///
-    /// It is important to note that the `beacon_state` returned may not match the present slot. It
-    /// is the state as it was when the head block was received, which could be some slots prior to
-    /// now.
-    pub fn head(&self) -> RwLockReadGuard<CheckPoint<T::EthSpec>> {
-        self.canonical_head.read()
-    }
-
-    /// Returns the slot of the highest block in the canonical chain.
-    pub fn best_slot(&self) -> Slot {
-        self.canonical_head.read().beacon_block.slot
+    /// Update the canonical head to `new_head`.
+    fn update_canonical_head(&self, new_head: CheckPoint<T::EthSpec>) -> Result<(), Error> {
+        // Update the checkpoint that stores the head of the chain at the time it received the
+        // block.
+        *self.canonical_head.write() = new_head;
+
+        // Update the always-at-the-present-slot state we keep around for performance gains.
+        *self.state.write() = {
+            let mut state = self.canonical_head.read().beacon_state.clone();
+
+            let present_slot = match self.slot_clock.present_slot() {
+                Ok(Some(slot)) => slot,
+                _ => return Err(Error::UnableToReadSlot),
+            };
+
+            // If required, transition the new state to the present slot.
+            for _ in state.slot.as_u64()..present_slot.as_u64() {
+                per_slot_processing(&mut state, &T::EthSpec::spec())?;
+            }
+
+            state.build_all_caches(&T::EthSpec::spec())?;
+
+            state
+        };
+
+        // Save `self` to `self.store`.
+        self.persist()?;
+
+        Ok(())
     }
 
+    /*
     /// Updates the canonical `BeaconState` with the supplied state.
     ///
     /// Advances the chain forward to the present slot. This method is better than just setting
@@ -362,10 +363,10 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
         // If required, transition the new state to the present slot.
         for _ in state.slot.as_u64()..present_slot.as_u64() {
-            per_slot_processing(&mut state, &self.spec)?;
+            per_slot_processing(&mut state, &T::EthSpec::spec())?;
         }
 
-        state.build_all_caches(&self.spec)?;
+        state.build_all_caches(&T::EthSpec::spec())?;
 
         *self.state.write() = state;
 
@@ -373,9 +374,33 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
         Ok(())
     }
+    */
+
+    /// Returns a read-lock guarded `BeaconState` which is the `canonical_head` that has been
+    /// updated to match the current slot clock.
+    pub fn current_state(&self) -> RwLockReadGuard<BeaconState<T::EthSpec>> {
+        self.state.read()
+    }
+
+    /// Returns a read-lock guarded `CheckPoint` struct for reading the head (as chosen by the
+    /// fork-choice rule).
+    ///
+    /// It is important to note that the `beacon_state` returned may not match the present slot. It
+    /// is the state as it was when the head block was received, which could be some slots prior to
+    /// now.
+    pub fn head(&self) -> RwLockReadGuard<CheckPoint<T::EthSpec>> {
+        self.canonical_head.read()
+    }
+
+    /// Returns the slot of the highest block in the canonical chain.
+    pub fn best_slot(&self) -> Slot {
+        self.canonical_head.read().beacon_block.slot
+    }
 
     /// Ensures the current canonical `BeaconState` has been transitioned to match the `slot_clock`.
     pub fn catchup_state(&self) -> Result<(), Error> {
+        let spec = &T::EthSpec::spec();
+
         let present_slot = match self.slot_clock.present_slot() {
             Ok(Some(slot)) => slot,
             _ => return Err(Error::UnableToReadSlot),
@@ -386,13 +411,13 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         // If required, transition the new state to the present slot.
         for _ in state.slot.as_u64()..present_slot.as_u64() {
             // Ensure the next epoch state caches are built in case of an epoch transition.
-            state.build_epoch_cache(RelativeEpoch::NextWithoutRegistryChange, &self.spec)?;
-            state.build_epoch_cache(RelativeEpoch::NextWithRegistryChange, &self.spec)?;
+            state.build_epoch_cache(RelativeEpoch::NextWithoutRegistryChange, spec)?;
+            state.build_epoch_cache(RelativeEpoch::NextWithRegistryChange, spec)?;
 
-            per_slot_processing(&mut *state, &self.spec)?;
+            per_slot_processing(&mut *state, spec)?;
         }
 
-        state.build_all_caches(&self.spec)?;
+        state.build_all_caches(spec)?;
 
         Ok(())
     }
@@ -401,34 +426,11 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     ///
     /// Ideally this shouldn't be required, however we leave it here for testing.
     pub fn ensure_state_caches_are_built(&self) -> Result<(), Error> {
-        self.state.write().build_all_caches(&self.spec)?;
+        self.state.write().build_all_caches(&T::EthSpec::spec())?;
 
         Ok(())
     }
 
-    /// Update the justified head to some new values.
-    fn update_finalized_head(
-        &self,
-        new_beacon_block: BeaconBlock,
-        new_beacon_block_root: Hash256,
-        new_beacon_state: BeaconState<T::EthSpec>,
-        new_beacon_state_root: Hash256,
-    ) {
-        let mut finalized_head = self.finalized_head.write();
-        finalized_head.update(
-            new_beacon_block,
-            new_beacon_block_root,
-            new_beacon_state,
-            new_beacon_state_root,
-        );
-    }
-
-    /// Returns a read-lock guarded `CheckPoint` struct for reading the justified head (as chosen,
-    /// indirectly,  by the fork-choice rule).
-    pub fn finalized_head(&self) -> RwLockReadGuard<CheckPoint<T::EthSpec>> {
-        self.finalized_head.read()
-    }
-
     /// Returns the validator index (if any) for the given public key.
     ///
     /// Information is retrieved from the present `beacon_state.validator_registry`.
@@ -467,13 +469,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// genesis.
     pub fn slots_since_genesis(&self) -> Option<SlotHeight> {
         let now = self.read_slot_clock()?;
+        let genesis_slot = T::EthSpec::spec().genesis_slot;
 
-        if now < self.spec.genesis_slot {
+        if now < genesis_slot {
             None
         } else {
-            Some(SlotHeight::from(
-                now.as_u64() - self.spec.genesis_slot.as_u64(),
-            ))
+            Some(SlotHeight::from(now.as_u64() - genesis_slot.as_u64()))
         }
     }
 
@@ -493,12 +494,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn block_proposer(&self, slot: Slot) -> Result<usize, BeaconStateError> {
         self.state
             .write()
-            .build_epoch_cache(RelativeEpoch::Current, &self.spec)?;
+            .build_epoch_cache(RelativeEpoch::Current, &T::EthSpec::spec())?;
 
         let index = self.state.read().get_beacon_proposer_index(
             slot,
             RelativeEpoch::Current,
-            &self.spec,
+            &T::EthSpec::spec(),
         )?;
 
         Ok(index)
@@ -519,7 +520,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         if let Some(attestation_duty) = self
             .state
             .read()
-            .get_attestation_duties(validator_index, &self.spec)?
+            .get_attestation_duties(validator_index, &T::EthSpec::spec())?
         {
             Ok(Some((attestation_duty.slot, attestation_duty.shard)))
         } else {
@@ -529,7 +530,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
     /// Produce an `AttestationData` that is valid for the present `slot` and given `shard`.
     pub fn produce_attestation_data(&self, shard: u64) -> Result<AttestationData, Error> {
-        trace!("BeaconChain::produce_attestation: shard: {}", shard);
+        let slots_per_epoch = T::EthSpec::spec().slots_per_epoch;
 
         self.metrics.attestation_production_requests.inc();
         let timer = self.metrics.attestation_production_times.start_timer();
@@ -540,8 +541,8 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             .state
             .read()
             .slot
-            .epoch(self.spec.slots_per_epoch)
-            .start_slot(self.spec.slots_per_epoch);
+            .epoch(slots_per_epoch)
+            .start_slot(slots_per_epoch);
 
         let target_root = if state.slot == current_epoch_start_slot {
             // If we're on the first slot of the state's epoch.
@@ -554,7 +555,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 *self
                     .state
                     .read()
-                    .get_block_root(current_epoch_start_slot - self.spec.slots_per_epoch)?
+                    .get_block_root(current_epoch_start_slot - slots_per_epoch)?
             }
         } else {
             // If we're not on the first slot of the epoch.
@@ -587,9 +588,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         self.metrics.attestation_processing_requests.inc();
         let timer = self.metrics.attestation_processing_times.start_timer();
 
-        let result = self
-            .op_pool
-            .insert_attestation(attestation, &*self.state.read(), &self.spec);
+        let result =
+            self.op_pool
+                .insert_attestation(attestation, &*self.state.read(), &T::EthSpec::spec());
 
         if result.is_ok() {
             self.metrics.attestation_production_successes.inc();
@@ -606,19 +607,19 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         deposit: Deposit,
     ) -> Result<DepositInsertStatus, DepositValidationError> {
         self.op_pool
-            .insert_deposit(deposit, &*self.state.read(), &self.spec)
+            .insert_deposit(deposit, &*self.state.read(), &T::EthSpec::spec())
     }
 
     /// Accept some exit and queue it for inclusion in an appropriate block.
     pub fn process_voluntary_exit(&self, exit: VoluntaryExit) -> Result<(), ExitValidationError> {
         self.op_pool
-            .insert_voluntary_exit(exit, &*self.state.read(), &self.spec)
+            .insert_voluntary_exit(exit, &*self.state.read(), &T::EthSpec::spec())
     }
 
     /// Accept some transfer and queue it for inclusion in an appropriate block.
     pub fn process_transfer(&self, transfer: Transfer) -> Result<(), TransferValidationError> {
         self.op_pool
-            .insert_transfer(transfer, &*self.state.read(), &self.spec)
+            .insert_transfer(transfer, &*self.state.read(), &T::EthSpec::spec())
     }
 
     /// Accept some proposer slashing and queue it for inclusion in an appropriate block.
@@ -626,8 +627,11 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         &self,
         proposer_slashing: ProposerSlashing,
     ) -> Result<(), ProposerSlashingValidationError> {
-        self.op_pool
-            .insert_proposer_slashing(proposer_slashing, &*self.state.read(), &self.spec)
+        self.op_pool.insert_proposer_slashing(
+            proposer_slashing,
+            &*self.state.read(),
+            &T::EthSpec::spec(),
+        )
     }
 
     /// Accept some attester slashing and queue it for inclusion in an appropriate block.
@@ -635,8 +639,11 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         &self,
         attester_slashing: AttesterSlashing,
     ) -> Result<(), AttesterSlashingValidationError> {
-        self.op_pool
-            .insert_attester_slashing(attester_slashing, &*self.state.read(), &self.spec)
+        self.op_pool.insert_attester_slashing(
+            attester_slashing,
+            &*self.state.read(),
+            &T::EthSpec::spec(),
+        )
     }
 
     /// Accept some block and attempt to add it to block DAG.
@@ -686,7 +693,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         // Transition the parent state to the block slot.
         let mut state: BeaconState<T::EthSpec> = parent_state;
         for _ in state.slot.as_u64()..block.slot.as_u64() {
-            if let Err(e) = per_slot_processing(&mut state, &self.spec) {
+            if let Err(e) = per_slot_processing(&mut state, &T::EthSpec::spec()) {
                 return Ok(BlockProcessingOutcome::InvalidBlock(
                     InvalidBlock::SlotProcessingError(e),
                 ));
@@ -695,7 +702,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
         // Apply the received block to its parent state (which has been transitioned into this
         // slot).
-        if let Err(e) = per_block_processing(&mut state, &block, &self.spec) {
+        if let Err(e) = per_block_processing(&mut state, &block, &T::EthSpec::spec()) {
             return Ok(BlockProcessingOutcome::InvalidBlock(
                 InvalidBlock::PerBlockProcessingError(e),
             ));
@@ -716,7 +723,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         // Register the new block with the fork choice service.
         self.fork_choice
             .write()
-            .add_block(&block, &block_root, &self.spec)?;
+            .add_block(&block, &block_root, &T::EthSpec::spec())?;
 
         // Execute the fork choice algorithm, enthroning a new head if discovered.
         //
@@ -744,7 +751,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
         let mut state = self.state.read().clone();
 
-        state.build_epoch_cache(RelativeEpoch::Current, &self.spec)?;
+        state.build_epoch_cache(RelativeEpoch::Current, &T::EthSpec::spec())?;
 
         trace!("Finding attestations for new block...");
 
@@ -752,14 +759,15 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             .get_block_root(state.slot - 1)
             .map_err(|_| BlockProductionError::UnableToGetBlockRootFromState)?;
 
-        let (proposer_slashings, attester_slashings) =
-            self.op_pool.get_slashings(&*self.state.read(), &self.spec);
+        let (proposer_slashings, attester_slashings) = self
+            .op_pool
+            .get_slashings(&*self.state.read(), &T::EthSpec::spec());
 
         let mut block = BeaconBlock {
             slot: state.slot,
             previous_block_root,
             state_root: Hash256::zero(), // Updated after the state is calculated.
-            signature: self.spec.empty_signature.clone(), // To be completed by a validator.
+            signature: T::EthSpec::spec().empty_signature.clone(), // To be completed by a validator.
             body: BeaconBlockBody {
                 randao_reveal,
                 eth1_data: Eth1Data {
@@ -771,12 +779,16 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 attester_slashings,
                 attestations: self
                     .op_pool
-                    .get_attestations(&*self.state.read(), &self.spec),
-                deposits: self.op_pool.get_deposits(&*self.state.read(), &self.spec),
+                    .get_attestations(&*self.state.read(), &T::EthSpec::spec()),
+                deposits: self
+                    .op_pool
+                    .get_deposits(&*self.state.read(), &T::EthSpec::spec()),
                 voluntary_exits: self
                     .op_pool
-                    .get_voluntary_exits(&*self.state.read(), &self.spec),
-                transfers: self.op_pool.get_transfers(&*self.state.read(), &self.spec),
+                    .get_voluntary_exits(&*self.state.read(), &T::EthSpec::spec()),
+                transfers: self
+                    .op_pool
+                    .get_transfers(&*self.state.read(), &T::EthSpec::spec()),
             },
         };
 
@@ -785,7 +797,11 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             block.body.attestations.len()
         );
 
-        per_block_processing_without_verifying_block_signature(&mut state, &block, &self.spec)?;
+        per_block_processing_without_verifying_block_signature(
+            &mut state,
+            &block,
+            &T::EthSpec::spec(),
+        )?;
 
         let state_root = state.canonical_root();
 
@@ -801,39 +817,53 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn fork_choice(&self) -> Result<(), Error> {
         self.metrics.fork_choice_requests.inc();
 
-        let present_head_root = self.finalized_head().beacon_block_root;
-
+        // Start fork choice metrics timer.
         let timer = self.metrics.fork_choice_times.start_timer();
 
-        let new_head_root = self
+        let justified_root = {
+            let root = self.head().beacon_state.current_justified_root;
+            if root == T::EthSpec::spec().zero_hash {
+                 self.genesis_block_root
+            } else {
+                root
+            }
+        };
+
+        // Determine the root of the block that is the head of the chain.
+        let beacon_block_root = self
             .fork_choice
             .write()
-            .find_head(&present_head_root, &self.spec)?;
+            .find_head(&justified_root, &T::EthSpec::spec())?;
 
+        // End fork choice metrics timer.
         timer.observe_duration();
 
-        if new_head_root != present_head_root {
+        // If a new head was chosen.
+        if beacon_block_root != self.head().beacon_block_root {
             self.metrics.fork_choice_changed_head.inc();
 
-            let block: BeaconBlock = self
+            let beacon_block: BeaconBlock = self
                 .store
-                .get(&new_head_root)?
-                .ok_or_else(|| Error::MissingBeaconBlock(new_head_root))?;
-            let state: BeaconState<T::EthSpec> = self
-                .store
-                .get(&block.state_root)?
-                .ok_or_else(|| Error::MissingBeaconState(block.state_root))?;
+                .get(&beacon_block_root)?
+                .ok_or_else(|| Error::MissingBeaconBlock(beacon_block_root))?;
 
-            // Log if we switched to a new chain.
-            if present_head_root != block.previous_block_root {
+            let beacon_state_root = beacon_block.state_root;
+            let beacon_state: BeaconState<T::EthSpec> = self
+                .store
+                .get(&beacon_state_root)?
+                .ok_or_else(|| Error::MissingBeaconState(beacon_state_root))?;
+
+            // If we switched to a new chain (instead of building atop the present chain).
+            if self.head().beacon_block_root != beacon_block.previous_block_root {
                 self.metrics.fork_choice_reorg_count.inc();
             };
 
-            let state_root = block.state_root;
-            self.update_canonical_head(block, new_head_root, state.clone(), state_root);
-
-            // Update the canonical `BeaconState`.
-            self.update_state(state)?;
+            self.update_canonical_head(CheckPoint {
+                beacon_block,
+                beacon_block_root,
+                beacon_state,
+                beacon_state_root,
+            })?;
         }
 
         Ok(())
@@ -863,7 +893,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         loop {
             let beacon_block_root = last_slot.beacon_block.previous_block_root;
 
-            if beacon_block_root == self.spec.zero_hash {
+            if beacon_block_root == T::EthSpec::spec().zero_hash {
                 break; // Genesis has been reached.
             }
 
diff --git a/beacon_node/beacon_chain/src/persisted_beacon_chain.rs b/beacon_node/beacon_chain/src/persisted_beacon_chain.rs
index cb34e995cd..f5bdfdee15 100644
--- a/beacon_node/beacon_chain/src/persisted_beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/persisted_beacon_chain.rs
@@ -2,7 +2,7 @@ use crate::{BeaconChainTypes, CheckPoint};
 use ssz::{Decode, Encode};
 use ssz_derive::{Decode, Encode};
 use store::{DBColumn, Error as StoreError, StoreItem};
-use types::BeaconState;
+use types::{BeaconState, Hash256};
 
 /// 32-byte key for accessing the `PersistedBeaconChain`.
 pub const BEACON_CHAIN_DB_KEY: &str = "PERSISTEDBEACONCHAINPERSISTEDBEA";
@@ -10,8 +10,8 @@ pub const BEACON_CHAIN_DB_KEY: &str = "PERSISTEDBEACONCHAINPERSISTEDBEA";
 #[derive(Encode, Decode)]
 pub struct PersistedBeaconChain<T: BeaconChainTypes> {
     pub canonical_head: CheckPoint<T::EthSpec>,
-    pub finalized_head: CheckPoint<T::EthSpec>,
     // TODO: operations pool.
+    pub genesis_block_root: Hash256,
     pub state: BeaconState<T::EthSpec>,
 }
 
diff --git a/beacon_node/client/src/beacon_chain_types.rs b/beacon_node/client/src/beacon_chain_types.rs
index 24ad93ad44..f84a7fdf65 100644
--- a/beacon_node/client/src/beacon_chain_types.rs
+++ b/beacon_node/client/src/beacon_chain_types.rs
@@ -1,5 +1,5 @@
 use beacon_chain::{
-    fork_choice::BitwiseLMDGhost,
+    fork_choice::OptimizedLMDGhost,
     slot_clock::SystemTimeSlotClock,
     store::{DiskStore, MemoryStore, Store},
     BeaconChain, BeaconChainTypes,
@@ -28,7 +28,7 @@ pub struct TestnetMemoryBeaconChainTypes;
 impl BeaconChainTypes for TestnetMemoryBeaconChainTypes {
     type Store = MemoryStore;
     type SlotClock = SystemTimeSlotClock;
-    type ForkChoice = BitwiseLMDGhost<Self::Store, Self::EthSpec>;
+    type ForkChoice = OptimizedLMDGhost<Self::Store, Self::EthSpec>;
     type EthSpec = LighthouseTestnetEthSpec;
 }
 
@@ -45,7 +45,7 @@ pub struct TestnetDiskBeaconChainTypes;
 impl BeaconChainTypes for TestnetDiskBeaconChainTypes {
     type Store = DiskStore;
     type SlotClock = SystemTimeSlotClock;
-    type ForkChoice = BitwiseLMDGhost<Self::Store, Self::EthSpec>;
+    type ForkChoice = OptimizedLMDGhost<Self::Store, Self::EthSpec>;
     type EthSpec = LighthouseTestnetEthSpec;
 }
 
diff --git a/beacon_node/client/src/lib.rs b/beacon_node/client/src/lib.rs
index 4824d40ad2..d29d00ad49 100644
--- a/beacon_node/client/src/lib.rs
+++ b/beacon_node/client/src/lib.rs
@@ -128,6 +128,7 @@ where
                 executor,
                 network_send,
                 beacon_chain.clone(),
+                config.db_name.clone(),
                 metrics_registry,
                 &log,
             ))
diff --git a/beacon_node/http_server/src/api.rs b/beacon_node/http_server/src/api.rs
index a910808998..2594f9c288 100644
--- a/beacon_node/http_server/src/api.rs
+++ b/beacon_node/http_server/src/api.rs
@@ -10,6 +10,7 @@ use persistent::Read;
 use router::Router;
 use serde_json::json;
 use std::sync::Arc;
+use types::EthSpec;
 
 /// Yields a handler for the HTTP API.
 pub fn build_handler<T: BeaconChainTypes + 'static>(
@@ -64,7 +65,7 @@ fn handle_fork<T: BeaconChainTypes + 'static>(req: &mut Request) -> IronResult<R
 
     let response = json!({
         "fork": beacon_chain.head().beacon_state.fork,
-        "chain_id": beacon_chain.spec.chain_id
+        "chain_id": T::EthSpec::spec().chain_id
     });
 
     Ok(Response::with((Status::Ok, response.to_string())))
diff --git a/beacon_node/http_server/src/key.rs b/beacon_node/http_server/src/key.rs
index b84c5f6857..a69da6747f 100644
--- a/beacon_node/http_server/src/key.rs
+++ b/beacon_node/http_server/src/key.rs
@@ -3,6 +3,7 @@ use beacon_chain::{BeaconChain, BeaconChainTypes};
 use iron::typemap::Key;
 use prometheus::Registry;
 use std::marker::PhantomData;
+use std::path::PathBuf;
 use std::sync::Arc;
 
 pub struct BeaconChainKey<T> {
@@ -24,3 +25,9 @@ pub struct LocalMetricsKey;
 impl Key for LocalMetricsKey {
     type Value = LocalMetrics;
 }
+
+pub struct DBPathKey;
+
+impl Key for DBPathKey {
+    type Value = PathBuf;
+}
diff --git a/beacon_node/http_server/src/lib.rs b/beacon_node/http_server/src/lib.rs
index cc54b6e17b..fb94348265 100644
--- a/beacon_node/http_server/src/lib.rs
+++ b/beacon_node/http_server/src/lib.rs
@@ -9,6 +9,7 @@ use network::NetworkMessage;
 use prometheus::Registry;
 use router::Router;
 use slog::{info, o, warn};
+use std::path::PathBuf;
 use std::sync::Arc;
 use tokio::runtime::TaskExecutor;
 
@@ -32,6 +33,7 @@ impl Default for HttpServerConfig {
 /// Build the `iron` HTTP server, defining the core routes.
 pub fn create_iron_http_server<T: BeaconChainTypes + 'static>(
     beacon_chain: Arc<BeaconChain<T>>,
+    db_path: PathBuf,
     metrics_registry: Registry,
 ) -> Iron<Router> {
     let mut router = Router::new();
@@ -39,7 +41,7 @@ pub fn create_iron_http_server<T: BeaconChainTypes + 'static>(
     // A `GET` request to `/metrics` is handled by the `metrics` module.
     router.get(
         "/metrics",
-        metrics::build_handler(beacon_chain.clone(), metrics_registry),
+        metrics::build_handler(beacon_chain.clone(), db_path, metrics_registry),
         "metrics",
     );
 
@@ -55,6 +57,7 @@ pub fn start_service<T: BeaconChainTypes + 'static>(
     executor: &TaskExecutor,
     _network_chan: crossbeam_channel::Sender<NetworkMessage>,
     beacon_chain: Arc<BeaconChain<T>>,
+    db_path: PathBuf,
     metrics_registry: Registry,
     log: &slog::Logger,
 ) -> exit_future::Signal {
@@ -66,7 +69,7 @@ pub fn start_service<T: BeaconChainTypes + 'static>(
     let (shutdown_trigger, wait_for_shutdown) = exit_future::signal();
 
     // Create an `iron` http, without starting it yet.
-    let iron = create_iron_http_server(beacon_chain, metrics_registry);
+    let iron = create_iron_http_server(beacon_chain, db_path, metrics_registry);
 
     // Create a HTTP server future.
     //
diff --git a/beacon_node/http_server/src/metrics.rs b/beacon_node/http_server/src/metrics.rs
index bfa80ec557..1b1ed1f3d4 100644
--- a/beacon_node/http_server/src/metrics.rs
+++ b/beacon_node/http_server/src/metrics.rs
@@ -1,19 +1,23 @@
 use crate::{
-    key::{BeaconChainKey, LocalMetricsKey, MetricsRegistryKey},
+    key::{BeaconChainKey, DBPathKey, LocalMetricsKey, MetricsRegistryKey},
     map_persistent_err_to_500,
 };
 use beacon_chain::{BeaconChain, BeaconChainTypes};
 use iron::prelude::*;
 use iron::{status::Status, Handler, IronResult, Request, Response};
 use persistent::Read;
-use prometheus::{Encoder, IntGauge, Opts, Registry, TextEncoder};
-use slot_clock::SlotClock;
+use prometheus::{Encoder, Registry, TextEncoder};
+use std::path::PathBuf;
 use std::sync::Arc;
-use types::Slot;
+
+pub use local_metrics::LocalMetrics;
+
+mod local_metrics;
 
 /// Yields a handler for the metrics endpoint.
 pub fn build_handler<T: BeaconChainTypes + 'static>(
     beacon_chain: Arc<BeaconChain<T>>,
+    db_path: PathBuf,
     metrics_registry: Registry,
 ) -> impl Handler {
     let mut chain = Chain::new(handle_metrics::<T>);
@@ -24,43 +28,11 @@ pub fn build_handler<T: BeaconChainTypes + 'static>(
     chain.link(Read::<BeaconChainKey<T>>::both(beacon_chain));
     chain.link(Read::<MetricsRegistryKey>::both(metrics_registry));
     chain.link(Read::<LocalMetricsKey>::both(local_metrics));
+    chain.link(Read::<DBPathKey>::both(db_path));
 
     chain
 }
 
-pub struct LocalMetrics {
-    present_slot: IntGauge,
-    best_slot: IntGauge,
-    validator_count: IntGauge,
-}
-
-impl LocalMetrics {
-    pub fn new() -> Result<Self, prometheus::Error> {
-        Ok(Self {
-            present_slot: {
-                let opts = Opts::new("present_slot", "slot_at_time_of_scrape");
-                IntGauge::with_opts(opts)?
-            },
-            best_slot: {
-                let opts = Opts::new("best_slot", "slot_of_block_at_chain_head");
-                IntGauge::with_opts(opts)?
-            },
-            validator_count: {
-                let opts = Opts::new("validator_count", "number_of_validators");
-                IntGauge::with_opts(opts)?
-            },
-        })
-    }
-
-    pub fn register(&self, registry: &Registry) -> Result<(), prometheus::Error> {
-        registry.register(Box::new(self.present_slot.clone()))?;
-        registry.register(Box::new(self.best_slot.clone()))?;
-        registry.register(Box::new(self.validator_count.clone()))?;
-
-        Ok(())
-    }
-}
-
 /// Handle a request for Prometheus metrics.
 ///
 /// Returns a text string containing all metrics.
@@ -77,18 +49,12 @@ fn handle_metrics<T: BeaconChainTypes + 'static>(req: &mut Request) -> IronResul
         .get::<Read<LocalMetricsKey>>()
         .map_err(map_persistent_err_to_500)?;
 
-    let present_slot = beacon_chain
-        .slot_clock
-        .present_slot()
-        .unwrap_or_else(|_| None)
-        .unwrap_or_else(|| Slot::new(0));
-    local_metrics.present_slot.set(present_slot.as_u64() as i64);
+    let db_path = req
+        .get::<Read<DBPathKey>>()
+        .map_err(map_persistent_err_to_500)?;
 
-    let best_slot = beacon_chain.head().beacon_block.slot;
-    local_metrics.best_slot.set(best_slot.as_u64() as i64);
-
-    let validator_count = beacon_chain.head().beacon_state.validator_registry.len();
-    local_metrics.validator_count.set(validator_count as i64);
+    // Update metrics that are calculated on each scrape.
+    local_metrics.update(&beacon_chain, &db_path);
 
     let mut buffer = vec![];
     let encoder = TextEncoder::new();
diff --git a/beacon_node/http_server/src/metrics/local_metrics.rs b/beacon_node/http_server/src/metrics/local_metrics.rs
new file mode 100644
index 0000000000..e2b0e6513b
--- /dev/null
+++ b/beacon_node/http_server/src/metrics/local_metrics.rs
@@ -0,0 +1,94 @@
+use beacon_chain::{BeaconChain, BeaconChainTypes};
+use prometheus::{IntGauge, Opts, Registry};
+use slot_clock::SlotClock;
+use std::path::PathBuf;
+use std::fs::File;
+use types::Slot;
+
+// If set to `true` will iterate and sum the balances of all validators in the state for each
+// scrape.
+const SHOULD_SUM_VALIDATOR_BALANCES: bool = true;
+
+pub struct LocalMetrics {
+    present_slot: IntGauge,
+    best_slot: IntGauge,
+    validator_count: IntGauge,
+    justified_epoch: IntGauge,
+    finalized_epoch: IntGauge,
+    validator_balances_sum: IntGauge,
+    database_size: IntGauge,
+}
+
+impl LocalMetrics {
+    /// Create a new instance.
+    pub fn new() -> Result<Self, prometheus::Error> {
+        Ok(Self {
+            present_slot: {
+                let opts = Opts::new("present_slot", "slot_at_time_of_scrape");
+                IntGauge::with_opts(opts)?
+            },
+            best_slot: {
+                let opts = Opts::new("best_slot", "slot_of_block_at_chain_head");
+                IntGauge::with_opts(opts)?
+            },
+            validator_count: {
+                let opts = Opts::new("validator_count", "number_of_validators");
+                IntGauge::with_opts(opts)?
+            },
+            justified_epoch: {
+                let opts = Opts::new("justified_epoch", "state_justified_epoch");
+                IntGauge::with_opts(opts)?
+            },
+            finalized_epoch: {
+                let opts = Opts::new("finalized_epoch", "state_finalized_epoch");
+                IntGauge::with_opts(opts)?
+            },
+            validator_balances_sum: {
+                let opts = Opts::new("validator_balances_sum", "sum_of_all_validator_balances");
+                IntGauge::with_opts(opts)?
+            },
+            database_size: {
+                let opts = Opts::new("database_size", "size_of_on_disk_db_in_mb");
+                IntGauge::with_opts(opts)?
+            },
+        })
+    }
+
+    /// Registry this instance with the `registry`.
+    pub fn register(&self, registry: &Registry) -> Result<(), prometheus::Error> {
+        registry.register(Box::new(self.present_slot.clone()))?;
+        registry.register(Box::new(self.best_slot.clone()))?;
+        registry.register(Box::new(self.validator_count.clone()))?;
+        registry.register(Box::new(self.finalized_epoch.clone()))?;
+        registry.register(Box::new(self.justified_epoch.clone()))?;
+        registry.register(Box::new(self.validator_balances_sum.clone()))?;
+        registry.register(Box::new(self.database_size.clone()))?;
+
+        Ok(())
+    }
+
+    /// Update the metrics in `self` to the latest values.
+    pub fn update<T: BeaconChainTypes>(&self, beacon_chain: &BeaconChain<T>, db_path: &PathBuf) {
+        let state = &beacon_chain.head().beacon_state;
+
+        let present_slot = beacon_chain
+            .slot_clock
+            .present_slot()
+            .unwrap_or_else(|_| None)
+            .unwrap_or_else(|| Slot::new(0));
+        self.present_slot.set(present_slot.as_u64() as i64);
+
+        self.best_slot.set(state.slot.as_u64() as i64);
+        self.validator_count.set(state.validator_registry.len() as i64);
+        self.justified_epoch.set(state.current_justified_epoch.as_u64() as i64);
+        self.finalized_epoch.set(state.finalized_epoch.as_u64() as i64);
+        if SHOULD_SUM_VALIDATOR_BALANCES {
+            self.validator_balances_sum.set(state.validator_balances.iter().sum::<u64>() as i64);
+        }
+        let db_size = File::open(db_path)
+            .and_then(|f| f.metadata())
+            .and_then(|m| Ok(m.len()))
+            .unwrap_or(0);
+        self.database_size.set(db_size as i64);
+    }
+}
diff --git a/beacon_node/network/src/sync/simple_sync.rs b/beacon_node/network/src/sync/simple_sync.rs
index 0ca4f60115..af6cbdfc03 100644
--- a/beacon_node/network/src/sync/simple_sync.rs
+++ b/beacon_node/network/src/sync/simple_sync.rs
@@ -859,7 +859,7 @@ fn hello_message<T: BeaconChainTypes>(beacon_chain: &BeaconChain<T>) -> HelloMes
         latest_finalized_root: state.finalized_root,
         latest_finalized_epoch: state.finalized_epoch,
         best_root: beacon_chain.head().beacon_block_root,
-        best_slot: beacon_chain.head().beacon_block.slot,
+        best_slot: state.slot,
     }
 }
 
diff --git a/beacon_node/rpc/src/attestation.rs b/beacon_node/rpc/src/attestation.rs
index e764e1b1d1..27fcad7cda 100644
--- a/beacon_node/rpc/src/attestation.rs
+++ b/beacon_node/rpc/src/attestation.rs
@@ -34,7 +34,7 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
         // verify the slot, drop lock on state afterwards
         {
             let slot_requested = req.get_slot();
-            let state = &self.chain.head().beacon_state;
+            let state = &self.chain.current_state();
 
             // Start by performing some checks
             // Check that the AttestionData is for the current slot (otherwise it will not be valid)
diff --git a/beacon_node/rpc/src/validator.rs b/beacon_node/rpc/src/validator.rs
index 4ab9588c4d..68ce60b969 100644
--- a/beacon_node/rpc/src/validator.rs
+++ b/beacon_node/rpc/src/validator.rs
@@ -30,7 +30,7 @@ impl<T: BeaconChainTypes> ValidatorService for ValidatorServiceInstance<T> {
         trace!(self.log, "RPC request"; "endpoint" => "GetValidatorDuties", "epoch" => req.get_epoch());
 
         let spec = T::EthSpec::spec();
-        let state = &self.chain.head().beacon_state;
+        let state = &self.chain.current_state();
         let epoch = Epoch::from(req.get_epoch());
         let mut resp = GetDutiesResponse::new();
         let resp_validators = resp.mut_active_validators();
diff --git a/validator_client/src/error.rs b/validator_client/src/error.rs
index 97500f900b..7740c4f2b6 100644
--- a/validator_client/src/error.rs
+++ b/validator_client/src/error.rs
@@ -1,6 +1,8 @@
 use slot_clock;
 
-use error_chain::error_chain;
+use error_chain::{
+    error_chain
+};
 
 error_chain! {
    links  { }