# UNDF: UNDF-2026-000000137
--- a/pkg/controller/garbagecollector/patch.go
+++ b/pkg/controller/garbagecollector/patch.go
@@ -17,7 +17,6 @@ package garbagecollector
 import (
 	"encoding/json"
-	"slices"

 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
@@ -108,11 +107,16 @@ func (gc *GarbageCollector) deleteOwnerRefJSONMergePatch(item *node, ownerUIDs .
 	expectedObjectMeta := ObjectMetaForPatch{}
 	expectedObjectMeta.ResourceVersion = accessor.GetResourceVersion()
 	refs := accessor.GetOwnerReferences()
+	// Build O(1) lookup set — avoids O(refs × ownerUIDs) with slices.Contains.
+	dropSet := make(map[types.UID]struct{}, len(ownerUIDs))
+	for _, uid := range ownerUIDs {
+		dropSet[uid] = struct{}{}
+	}
 	for _, ref := range refs {
-		if !slices.Contains(ownerUIDs, ref.UID) {
+		if _, drop := dropSet[ref.UID]; !drop {
 			expectedObjectMeta.OwnerReferences = append(expectedObjectMeta.OwnerReferences, ref)
 		}
 	}
 	return json.Marshal(objectForPatch{expectedObjectMeta})
 }