Improve D&D registry normalization efficiency

internal/modules/dnd/normalize/itemregistry/normalizer.go

@@ -241,20 +241,15 @@ func normalizeRecord(input dnd.Item, order shared.SourceRefOrder) (dnd.Item, boo
 
 func comparisonNameGroups(records []normalizedRecord) [][]int {
 	groups := make([][]int, 0, len(records))
+	groupPositions := make(map[string]int, len(records))
 	for index, record := range records {
 		key := identity.ComparisonKey(record.item.Name)
-		found := false
-		for groupIndex, members := range groups {
-			first := records[members[0]]
-			if identity.ComparisonKey(first.item.Name) == key {
-				groups[groupIndex] = append(groups[groupIndex], index)
-				found = true
-				break
-			}
-		}
-		if !found {
-			groups = append(groups, []int{index})
+		if groupIndex, found := groupPositions[key]; found {
+			groups[groupIndex] = append(groups[groupIndex], index)
+			continue
 		}
+		groupPositions[key] = len(groups)
+		groups = append(groups, []int{index})
 	}
 	return groups
 }

internal/modules/dnd/normalize/itemregistry/normalizer_test.go

@@ -85,6 +85,20 @@ func TestNormalizeConsolidatesEqualNamesAcrossEvidenceWithoutMutation(t *testing
 	}
 }
 
+func BenchmarkComparisonNameGroupsManyDistinct(b *testing.B) {
+	records := make([]normalizedRecord, 1_000)
+	for index := range records {
+		records[index] = normalizedRecord{item: dnd.Item{Name: "Item " + strconv.Itoa(index)}}
+	}
+	b.ReportAllocs()
+	b.ResetTimer()
+	for iteration := 0; iteration < b.N; iteration++ {
+		if groups := comparisonNameGroups(records); len(groups) != len(records) {
+			b.Fatalf("group count = %d, want %d", len(groups), len(records))
+		}
+	}
+}
+
 func TestNormalizeAppliesSafeAliasProposal(t *testing.T) {
 	doc := semanticDocument()
 	input := dnd.ItemRegistry{Items: []dnd.Item{