diff --git a/src/routes/api/proposals/voters/add/+server.ts b/src/routes/api/proposals/voters/add/+server.ts
index 62f2caf8..62f8d586 100644
--- a/src/routes/api/proposals/voters/add/+server.ts
+++ b/src/routes/api/proposals/voters/add/+server.ts
@@ -23,7 +23,9 @@ export async function GET() {
 			?.setValue()
 			.values.map((voter) => voter.addressValue().value.toString('hex')) ?? [];
 
-	const newVoters = owners.filter((owner) => !voters.includes(owner)).slice(0, 50);
+	// Optimize O(N*M) lookup to O(N) using a Set
+	const votersSet = new Set(voters);
+	const newVoters = owners.filter((owner) => !votersSet.has(owner)).slice(0, 50);
 	if (newVoters.length === 0) return json({ newVoters }, { status: 200 });
 
 	const votingContract = await metaNamesSdk.contractRepository.getContract({
diff --git a/src/routes/api/proposals/voters/remove/+server.ts b/src/routes/api/proposals/voters/remove/+server.ts
index d024e90f..02ffdc40 100644
--- a/src/routes/api/proposals/voters/remove/+server.ts
+++ b/src/routes/api/proposals/voters/remove/+server.ts
@@ -25,7 +25,9 @@ export async function GET() {
 			?.setValue()
 			.values.map((voter) => voter.addressValue().value.toString('hex')) ?? [];
 
-	const votersToRemove = voters.filter((voter) => !owners.includes(voter)).slice(0, 50);
+	// Optimize O(N*M) lookup to O(N) using a Set
+	const ownersSet = new Set(owners);
+	const votersToRemove = voters.filter((voter) => !ownersSet.has(voter)).slice(0, 50);
 	if (votersToRemove.length === 0) return json({ newVoters: votersToRemove }, { status: 200 });
 
 	const votingContract = await metaNamesSdk.contractRepository.getContract({