# UNDF: UNDF-2026-000001015
--- a/allocate.go
+++ b/allocate.go
@@ -123,11 +123,22 @@ func (c *Cluster) filterMetrics(ctx context.Context, mSet api.MetricsSet, numMet
 // For a metric/peer to be included in a group, it is necessary that it has
 // metrics for all informers.
 func (c *Cluster) filterMetrics(ctx context.Context, mSet api.MetricsSet, numMetrics int, currentAllocs, priorityList, blacklist []peer.ID) classifiedMetrics {
 	curPeersMap := make(map[peer.ID][]api.Metric)
 	candPeersMap := make(map[peer.ID][]api.Metric)
 	prioPeersMap := make(map[peer.ID][]api.Metric)

-	// Divide the metric by current/candidate/prio and by peer
+	// Build O(1) lookup sets for peer classification.
+	blacklistSet := make(map[peer.ID]struct{}, len(blacklist))
+	for _, p := range blacklist {
+		blacklistSet[p] = struct{}{}
+	}
+	currentAllocsSet := make(map[peer.ID]struct{}, len(currentAllocs))
+	for _, p := range currentAllocs {
+		currentAllocsSet[p] = struct{}{}
+	}
+	prioritySet := make(map[peer.ID]struct{}, len(priorityList))
+	for _, p := range priorityList {
+		prioritySet[p] = struct{}{}
+	}
+
+	// Divide our metrics by current/candidate/prio and by peer
 	for _, metrics := range mSet {
 		for _, m := range metrics {
 			switch {
-			case containsPeer(blacklist, m.Peer):
+			case peerInSet(blacklistSet, m.Peer):
 				// discard blacklisted peers
 				continue
 			case c.config.PinOnlyOnTrustedPeers && !c.consensus.IsTrustedPeer(ctx, m.Peer):
@@ -136,9 +147,9 @@ func (c *Cluster) filterMetrics(ctx context.Context, mSet api.MetricsSet, numMet
 			case c.config.PinOnlyOnUntrustedPeers && c.consensus.IsTrustedPeer(ctx, m.Peer):
 				// discard peers that are trusted
 				continue
-			case containsPeer(currentAllocs, m.Peer):
+			case peerInSet(currentAllocsSet, m.Peer):
 				curPeersMap[m.Peer] = append(curPeersMap[m.Peer], m)
-			case containsPeer(priorityList, m.Peer):
+			case peerInSet(prioritySet, m.Peer):
 				prioPeersMap[m.Peer] = append(prioPeersMap[m.Peer], m)
 			default:
 				candPeersMap[m.Peer] = append(candPeersMap[m.Peer], m)
--- a/util.go
+++ b/util.go
@@ -72,6 +72,12 @@ func containsPeer(list []peer.ID, peer peer.ID) bool {
 	return false
 }

+// peerInSet checks for peer membership in a pre-built set. O(1) average.
+func peerInSet(set map[peer.ID]struct{}, p peer.ID) bool {
+	_, ok := set[p]
+	return ok
+}
+
 func minInt(x, y int) int {
 	if x < y {
 		return x