diff --git a/yarn-project/aztec-node/src/aztec-node/server.ts b/yarn-project/aztec-node/src/aztec-node/server.ts
index dd29b991f0cf..6049767b8fee 100644
--- a/yarn-project/aztec-node/src/aztec-node/server.ts
+++ b/yarn-project/aztec-node/src/aztec-node/server.ts
@@ -845,6 +845,8 @@ export class AztecNodeService implements AztecNode, Traceable {
     }
   }
 
+  // TODO(md): change this to run in parrel the same as in the p2p client - maybe not required
+  // as everything is sub ms apart from the double spend validator
   public async isValidTx(tx: Tx, isSimulation: boolean = false): Promise<boolean> {
     const blockNumber = (await this.blockSource.getBlockNumber()) + 1;
     const db = this.worldStateSynchronizer.getCommitted();
@@ -855,9 +857,8 @@ export class AztecNodeService implements AztecNode, Traceable {
       new DataTxValidator(),
       new MetadataTxValidator(new Fr(this.l1ChainId), new Fr(blockNumber)),
       new DoubleSpendTxValidator({
-        getNullifierIndex(nullifier) {
-          return db.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, [nullifier.toBuffer()]).then(x => x[0]);
-        },
+        getNullifierIndices: nullifiers =>
+          db.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, nullifiers).then(x => x.filter(index => index !== undefined) as bigint[]),
       }),
     ];
 
diff --git a/yarn-project/p2p/src/services/libp2p/libp2p_service.ts b/yarn-project/p2p/src/services/libp2p/libp2p_service.ts
index 378cfd7f78c7..f7f196135bd9 100644
--- a/yarn-project/p2p/src/services/libp2p/libp2p_service.ts
+++ b/yarn-project/p2p/src/services/libp2p/libp2p_service.ts
@@ -603,10 +603,10 @@ export class LibP2PService<T extends P2PClientType> extends WithTracer implement
       },
       doubleSpendValidator: {
         validator: new DoubleSpendTxValidator({
-          getNullifierIndex: async (nullifier: Fr) => {
+          getNullifierIndices: async (nullifiers: Buffer[]) => {
             const merkleTree = this.worldStateSynchronizer.getCommitted();
-            const index = (await merkleTree.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, [nullifier.toBuffer()]))[0];
-            return index;
+            const indices = await merkleTree.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, nullifiers);
+            return indices.filter(index => index !== undefined) as bigint[];
           },
         }),
         severity: PeerErrorSeverity.HighToleranceError,
@@ -669,12 +669,12 @@ export class LibP2PService<T extends P2PClientType> extends WithTracer implement
     }
 
     const snapshotValidator = new DoubleSpendTxValidator({
-      getNullifierIndex: async (nullifier: Fr) => {
+      getNullifierIndices: async (nullifiers: Buffer[]) => {
         const merkleTree = this.worldStateSynchronizer.getSnapshot(
           blockNumber - this.config.severePeerPenaltyBlockLength,
         );
-        const index = (await merkleTree.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, [nullifier.toBuffer()]))[0];
-        return index;
+        const indices = await merkleTree.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, nullifiers);
+        return indices.filter(index => index !== undefined) as bigint[];
       },
     });
 
diff --git a/yarn-project/p2p/src/tx_validator/double_spend_validator.test.ts b/yarn-project/p2p/src/tx_validator/double_spend_validator.test.ts
index 1c123319f33e..e90d4b242f14 100644
--- a/yarn-project/p2p/src/tx_validator/double_spend_validator.test.ts
+++ b/yarn-project/p2p/src/tx_validator/double_spend_validator.test.ts
@@ -10,7 +10,7 @@ describe('DoubleSpendTxValidator', () => {
 
   beforeEach(() => {
     nullifierSource = mock<NullifierSource>({
-      getNullifierIndex: mockFn().mockImplementation(() => {
+      getNullifierIndices: mockFn().mockImplementation(() => {
         return Promise.resolve(undefined);
       }),
     });
@@ -48,7 +48,7 @@ describe('DoubleSpendTxValidator', () => {
 
   it('rejects duplicates against history', async () => {
     const badTx = mockTx();
-    nullifierSource.getNullifierIndex.mockReturnValueOnce(Promise.resolve(1n));
+    nullifierSource.getNullifierIndices.mockReturnValueOnce(Promise.resolve([1n]));
     await expect(txValidator.validateTxs([badTx])).resolves.toEqual([[], [badTx]]);
   });
 });
diff --git a/yarn-project/p2p/src/tx_validator/double_spend_validator.ts b/yarn-project/p2p/src/tx_validator/double_spend_validator.ts
index 5bb06bf1fa9d..81538eaea342 100644
--- a/yarn-project/p2p/src/tx_validator/double_spend_validator.ts
+++ b/yarn-project/p2p/src/tx_validator/double_spend_validator.ts
@@ -3,7 +3,7 @@ import { Fr } from '@aztec/circuits.js';
 import { createLogger } from '@aztec/foundation/log';
 
 export interface NullifierSource {
-  getNullifierIndex: (nullifier: Fr) => Promise<bigint | undefined>;
+  getNullifierIndices: (nullifiers: Buffer[]) => Promise<bigint[]>;
 }
 
 export class DoubleSpendTxValidator<T extends AnyTx> implements TxValidator<T> {
@@ -36,9 +36,7 @@ export class DoubleSpendTxValidator<T extends AnyTx> implements TxValidator<T> {
   }
 
   async #uniqueNullifiers(tx: AnyTx, thisBlockNullifiers: Set<bigint>): Promise<boolean> {
-    const nullifiers = (tx instanceof Tx ? tx.data.getNonEmptyNullifiers() : tx.txEffect.nullifiers).map(x =>
-      x.toBigInt(),
-    );
+    const nullifiers = (tx instanceof Tx ? tx.data.getNonEmptyNullifiers() : tx.txEffect.nullifiers);
 
     // Ditch this tx if it has repeated nullifiers
     const uniqueNullifiers = new Set(nullifiers);
@@ -48,7 +46,8 @@ export class DoubleSpendTxValidator<T extends AnyTx> implements TxValidator<T> {
     }
 
     if (this.isValidatingBlock) {
-      for (const nullifier of nullifiers) {
+      // TODO: remove all this type casting
+      for (const nullifier of nullifiers.map(n => n.toBigInt())) {
         if (thisBlockNullifiers.has(nullifier)) {
           this.#log.warn(`Rejecting tx ${Tx.getHash(tx)} for repeating a nullifier in the same block`);
           return false;
@@ -58,7 +57,7 @@ export class DoubleSpendTxValidator<T extends AnyTx> implements TxValidator<T> {
       }
     }
 
-    const nullifierIndexes = await Promise.all(nullifiers.map(n => this.#nullifierSource.getNullifierIndex(new Fr(n))));
+    const nullifierIndexes = await this.#nullifierSource.getNullifierIndices(nullifiers.map(n => n.toBuffer()));
 
     const hasDuplicates = nullifierIndexes.some(index => index !== undefined);
     if (hasDuplicates) {
diff --git a/yarn-project/sequencer-client/src/tx_validator/tx_validator_factory.ts b/yarn-project/sequencer-client/src/tx_validator/tx_validator_factory.ts
index dd36e4ebc3d9..13d02329ff17 100644
--- a/yarn-project/sequencer-client/src/tx_validator/tx_validator_factory.ts
+++ b/yarn-project/sequencer-client/src/tx_validator/tx_validator_factory.ts
@@ -29,8 +29,8 @@ export class TxValidatorFactory {
     private enforceFees: boolean,
   ) {
     this.nullifierSource = {
-      getNullifierIndex: nullifier =>
-        this.committedDb.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, [nullifier.toBuffer()]).then(x => x[0]),
+      getNullifierIndices: nullifiers =>
+        this.committedDb.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, nullifiers).then(x => x.filter(index => index !== undefined) as bigint[]),
     };
 
     this.publicStateSource = {
@@ -52,8 +52,8 @@ export class TxValidatorFactory {
 
   validatorForProcessedTxs(fork: MerkleTreeReadOperations): TxValidator<ProcessedTx> {
     return new DoubleSpendTxValidator({
-      getNullifierIndex: nullifier =>
-        fork.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, [nullifier.toBuffer()]).then(x => x[0]),
+      getNullifierIndices: nullifiers =>
+        fork.findLeafIndices(MerkleTreeId.NULLIFIER_TREE, nullifiers).then(x => x.filter(index => index !== undefined) as bigint[]),
     });
   }
 }