diff --git a/beacon_chain/spec/state_transition_epoch.nim b/beacon_chain/spec/state_transition_epoch.nim
index e767679d0..81f032221 100644
--- a/beacon_chain/spec/state_transition_epoch.nim
+++ b/beacon_chain/spec/state_transition_epoch.nim
@@ -268,6 +268,7 @@ func get_eligible_validator_indices(state: BeaconState): seq[ValidatorIndex] =
 
 func get_attestation_component_deltas(state: BeaconState,
                                       attestations: seq[PendingAttestation],
+                                      total_balance: Gwei,
                                       cache: var StateCache,
                                       ): tuple[a: seq[Gwei], b: seq[Gwei]] =
   # Helper with shared logic for use by get source, target, and head deltas
@@ -276,7 +277,6 @@ func get_attestation_component_deltas(state: BeaconState,
     rewards = repeat(0'u64, len(state.validators))
     penalties = repeat(0'u64, len(state.validators))
   let
-    total_balance = get_total_active_balance(state, cache)
     unslashed_attesting_indices =
       get_unslashed_attesting_indices(state, attestations, cache)
     attesting_balance = get_total_balance(state, unslashed_attesting_indices)
@@ -298,28 +298,36 @@ func get_attestation_component_deltas(state: BeaconState,
   (rewards, penalties)
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/beacon-chain.md#components-of-attestation-deltas
-func get_source_deltas(state: BeaconState, cache: var StateCache):
+# These is slightly refactored to calculate total_balance once.
+func get_source_deltas(
+    state: BeaconState, total_balance: Gwei, cache: var StateCache):
     tuple[a: seq[Gwei], b: seq[Gwei]] =
   # Return attester micro-rewards/penalties for source-vote for each validator.
   let matching_source_attestations =
     get_matching_source_attestations(state, get_previous_epoch(state))
-  get_attestation_component_deltas(state, matching_source_attestations, cache)
+  get_attestation_component_deltas(
+    state, matching_source_attestations, total_balance, cache)
 
-func get_target_deltas(state: BeaconState, cache: var StateCache):
+func get_target_deltas(
+    state: BeaconState, total_balance: Gwei, cache: var StateCache):
     tuple[a: seq[Gwei], b: seq[Gwei]] =
   # Return attester micro-rewards/penalties for target-vote for each validator.
   let matching_target_attestations =
     get_matching_target_attestations(state, get_previous_epoch(state))
-  get_attestation_component_deltas(state, matching_target_attestations, cache)
+  get_attestation_component_deltas(
+    state, matching_target_attestations, total_balance, cache)
 
-func get_head_deltas(state: BeaconState, cache: var StateCache):
+func get_head_deltas(
+    state: BeaconState, total_balance: Gwei, cache: var StateCache):
     tuple[a: seq[Gwei], b: seq[Gwei]] =
   # Return attester micro-rewards/penalties for head-vote for each validator.
   let matching_head_attestations =
     get_matching_head_attestations(state, get_previous_epoch(state))
-  get_attestation_component_deltas(state, matching_head_attestations, cache)
+  get_attestation_component_deltas(
+    state, matching_head_attestations, total_balance, cache)
 
-func get_inclusion_delay_deltas(state: BeaconState, cache: var StateCache):
+func get_inclusion_delay_deltas(
+    state: BeaconState, total_balance: Gwei, cache: var StateCache):
     seq[Gwei] =
   # Return proposer and inclusion delay micro-rewards/penalties for each validator.
   var rewards = repeat(0'u64, len(state.validators))
@@ -330,7 +338,6 @@ func get_inclusion_delay_deltas(state: BeaconState, cache: var StateCache):
       matching_source_attestations,
       get_attesting_indices(state, it.data, it.aggregation_bits, cache))
 
-  let total_balance = get_total_active_balance(state, cache)
   for index in get_unslashed_attesting_indices(state, matching_source_attestations, cache):
     # Translation of attestation = min([...])
     # Start by filtering the right attestations
@@ -363,11 +370,11 @@ func get_inclusion_delay_deltas(state: BeaconState, cache: var StateCache):
   # Spec constructs both and returns both; this doesn't
   rewards
 
-func get_inactivity_penalty_deltas(state: BeaconState, cache: var StateCache):
+func get_inactivity_penalty_deltas(
+    state: BeaconState, total_balance: Gwei, cache: var StateCache):
     seq[Gwei] =
   # Return inactivity reward/penalty deltas for each validator.
   var penalties = repeat(0'u64, len(state.validators))
-  let total_balance = get_total_active_balance(state, cache)
   if is_in_inactivity_leak(state):
     let
       matching_target_attestations =
@@ -392,14 +399,21 @@ func get_inactivity_penalty_deltas(state: BeaconState, cache: var StateCache):
   penalties
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/beacon-chain.md#get_attestation_deltas
-func get_attestation_deltas(state: BeaconState, cache: var StateCache): tuple[a: seq[Gwei], b: seq[Gwei]] =
+func get_attestation_deltas(state: BeaconState, cache: var StateCache):
+    tuple[a: seq[Gwei], b: seq[Gwei]] =
   # Return attestation reward/penalty deltas for each validator.
   let
-    (source_rewards, source_penalties) = get_source_deltas(state, cache)
-    (target_rewards, target_penalties) = get_target_deltas(state, cache)
-    (head_rewards, head_penalties) = get_head_deltas(state, cache)
-    inclusion_delay_rewards = get_inclusion_delay_deltas(state, cache)
-    inactivity_penalties = get_inactivity_penalty_deltas(state, cache)
+    total_balance = get_total_active_balance(state, cache)
+    (source_rewards, source_penalties) =
+      get_source_deltas(state, total_balance, cache)
+    (target_rewards, target_penalties) =
+      get_target_deltas(state, total_balance, cache)
+    (head_rewards, head_penalties) =
+      get_head_deltas(state, total_balance, cache)
+    inclusion_delay_rewards =
+      get_inclusion_delay_deltas(state, total_balance, cache)
+    inactivity_penalties =
+      get_inactivity_penalty_deltas(state, total_balance, cache)
 
   let rewards = mapIt(0 ..< len(state.validators),
     source_rewards[it] + target_rewards[it] + head_rewards[it] +