diff --git a/packages/state-transition/src/block/processEth1Data.ts b/packages/state-transition/src/block/processEth1Data.ts
index 2b6d8b62d79c..fe40f026028a 100644
--- a/packages/state-transition/src/block/processEth1Data.ts
+++ b/packages/state-transition/src/block/processEth1Data.ts
@@ -1,5 +1,5 @@
 import {Node} from "@chainsafe/persistent-merkle-tree";
-import {CompositeViewDU} from "@chainsafe/ssz";
+import {CompositeViewDU, ReusableListIterator} from "@chainsafe/ssz";
 import {EPOCHS_PER_ETH1_VOTING_PERIOD, SLOTS_PER_EPOCH} from "@lodestar/params";
 import {phase0, ssz} from "@lodestar/types";
 import {BeaconStateAllForks, CachedBeaconStateAllForks} from "../types.js";
@@ -26,7 +26,7 @@ export function processEth1Data(state: CachedBeaconStateAllForks, eth1Data: phas
 /**
  * This data is reused and never gc.
  */
-const eth1DataVotes = new Array<CompositeViewDU<typeof ssz.phase0.Eth1Data>>();
+const eth1DataVotes = new ReusableListIterator<CompositeViewDU<typeof ssz.phase0.Eth1Data>>();
 /**
  * Returns true if adding the given `eth1Data` to `state.eth1DataVotes` would
  * result in a change to `state.eth1Data`.
@@ -52,11 +52,11 @@ export function becomesNewEth1Data(
   // Then isEqualEth1DataView compares cached roots (HashObject as of Jan 2022) which is much cheaper
   // than doing structural equality, which requires tree -> value conversions
   let sameVotesCount = 0;
-  // const eth1DataVotes = state.eth1DataVotes.getAllReadonly();
-  eth1DataVotes.length = state.eth1DataVotes.length;
-  state.eth1DataVotes.getAllReadonly(eth1DataVotes);
-  for (let i = 0; i < eth1DataVotes.length; i++) {
-    if (isEqualEth1DataView(eth1DataVotes[i], newEth1Data)) {
+  eth1DataVotes.reset();
+  state.eth1DataVotes.getAllReadonlyIter(eth1DataVotes);
+  eth1DataVotes.clean();
+  for (const eth1DataVote of eth1DataVotes) {
+    if (isEqualEth1DataView(eth1DataVote, newEth1Data)) {
       sameVotesCount++;
     }
   }
diff --git a/packages/state-transition/src/cache/epochTransitionCache.ts b/packages/state-transition/src/cache/epochTransitionCache.ts
index 705966c58a67..0c0a908ecc15 100644
--- a/packages/state-transition/src/cache/epochTransitionCache.ts
+++ b/packages/state-transition/src/cache/epochTransitionCache.ts
@@ -16,6 +16,7 @@ import {
 import {CachedBeaconStateAllForks, CachedBeaconStateAltair, CachedBeaconStatePhase0} from "../index.js";
 import {computeBaseRewardPerIncrement} from "../util/altair.js";
 import {processPendingAttestations} from "../epoch/processPendingAttestations.js";
+import {ReusableListIterator} from "@chainsafe/ssz";
 
 export type EpochTransitionCacheOpts = {
   /**
@@ -200,7 +201,7 @@ const flags = new Array<number>();
 /**
  * This data is reused and never gc.
  */
-const validators = new Array<phase0.Validator>();
+const validators = new ReusableListIterator<phase0.Validator>();
 const previousEpochParticipation = new Array<number>();
 const currentEpochParticipation = new Array<number>();
 
@@ -221,7 +222,7 @@ export function beforeProcessEpoch(
   const eligibleValidatorIndices: ValidatorIndex[] = [];
   const indicesToSlash: ValidatorIndex[] = [];
   const indicesEligibleForActivationQueue: ValidatorIndex[] = [];
-  const indicesEligibleForActivation: ValidatorIndex[] = [];
+  const indicesEligibleForActivation: {validatorIndex: ValidatorIndex; activationEligibilityEpoch: Epoch}[] = [];
   const indicesToEject: ValidatorIndex[] = [];
   const nextEpochShufflingActiveValidatorIndices: ValidatorIndex[] = [];
 
@@ -230,8 +231,9 @@ export function beforeProcessEpoch(
   // To optimize memory each validator node in `state.validators` is represented with a special node type
   // `BranchNodeStruct` that represents the data as struct internally. This utility grabs the struct data directly
   // from the nodes without any extra transformation. The returned `validators` array contains native JS objects.
-  validators.length = state.validators.length;
-  state.validators.getAllReadonlyValues(validators);
+  validators.reset();
+  state.validators.getAllReadonlyValuesIter(validators);
+  validators.clean();
 
   const validatorCount = validators.length;
 
@@ -266,8 +268,9 @@ export function beforeProcessEpoch(
 
   const effectiveBalancesByIncrements = epochCtx.effectiveBalanceIncrements;
 
-  for (let i = 0; i < validatorCount; i++) {
-    const validator = validators[i];
+  // for (let i = 0; i < validatorCount; i++) {
+  let i = 0;
+  for (const validator of validators) {
     let flag = 0;
 
     if (validator.slashed) {
@@ -333,7 +336,7 @@ export function beforeProcessEpoch(
     //
     // Use `else` since indicesEligibleForActivationQueue + indicesEligibleForActivation are mutually exclusive
     else if (validator.activationEpoch === FAR_FUTURE_EPOCH && validator.activationEligibilityEpoch <= currentEpoch) {
-      indicesEligibleForActivation.push(i);
+      indicesEligibleForActivation.push({validatorIndex: i, activationEligibilityEpoch: validator.activationEligibilityEpoch});
     }
 
     // To optimize process_registry_updates():
@@ -358,6 +361,7 @@ export function beforeProcessEpoch(
     if (isActiveNext2) {
       nextEpochShufflingActiveValidatorIndices.push(i);
     }
+    i++;
   }
 
   if (totalActiveStakeByIncrement < 1) {
@@ -372,7 +376,7 @@ export function beforeProcessEpoch(
   // To optimize process_registry_updates():
   // order by sequence of activationEligibilityEpoch setting and then index
   indicesEligibleForActivation.sort(
-    (a, b) => validators[a].activationEligibilityEpoch - validators[b].activationEligibilityEpoch || a - b
+    (a, b) => a.activationEligibilityEpoch - b.activationEligibilityEpoch || a.validatorIndex - b.validatorIndex
   );
 
   if (forkSeq === ForkSeq.phase0) {
@@ -480,7 +484,7 @@ export function beforeProcessEpoch(
     eligibleValidatorIndices,
     indicesToSlash,
     indicesEligibleForActivationQueue,
-    indicesEligibleForActivation,
+    indicesEligibleForActivation: indicesEligibleForActivation.map(({validatorIndex}) => validatorIndex),
     indicesToEject,
     nextEpochShufflingActiveValidatorIndices,
     // to be updated in processEffectiveBalanceUpdates
diff --git a/packages/state-transition/src/util/balance.ts b/packages/state-transition/src/util/balance.ts
index edff9acef134..e14a18ab6606 100644
--- a/packages/state-transition/src/util/balance.ts
+++ b/packages/state-transition/src/util/balance.ts
@@ -4,6 +4,7 @@ import {bigIntMax} from "@lodestar/utils";
 import {EffectiveBalanceIncrements} from "../cache/effectiveBalanceIncrements.js";
 import {BeaconStateAllForks} from "..";
 import {CachedBeaconStateAllForks} from "../types.js";
+import {ReusableListIterator} from "@chainsafe/ssz";
 
 /**
  * Return the combined effective balance of the [[indices]].
@@ -46,7 +47,7 @@ export function decreaseBalance(state: BeaconStateAllForks, index: ValidatorInde
 /**
  * This data is reused and never gc.
  */
-const validators = new Array<phase0.Validator>();
+const validators = new ReusableListIterator<phase0.Validator>();
 
 /**
  * This method is used to get justified balances from a justified state.
@@ -68,14 +69,16 @@ export function getEffectiveBalanceIncrementsZeroInactive(
     validatorCount
   );
 
-  validators.length = validatorCount;
-  justifiedState.validators.getAllReadonlyValues(validators);
+  validators.reset();
+  justifiedState.validators.getAllReadonlyValuesIter(validators);
+  validators.clean();
+  let i = 0;
   let j = 0;
-  for (let i = 0; i < validatorCount; i++) {
+  for (const validator of validators) {
     if (i === activeIndices[j]) {
       // active validator
       j++;
-      if (validators[i].slashed) {
+      if (validator.slashed) {
         // slashed validator
         effectiveBalanceIncrementsZeroInactive[i] = 0;
       }
@@ -83,6 +86,7 @@ export function getEffectiveBalanceIncrementsZeroInactive(
       // inactive validator
       effectiveBalanceIncrementsZeroInactive[i] = 0;
     }
+    i++;
   }
 
   return effectiveBalanceIncrementsZeroInactive;