diff --git a/mapper/benchmark_test.go b/mapper/benchmark_test.go
new file mode 100644
index 0000000..0e7cccb
--- /dev/null
+++ b/mapper/benchmark_test.go
@@ -0,0 +1,186 @@
+package mapper
+
+import (
+	"testing"
+
+	"github.com/KorAP/KoralPipe-TermMapper/config"
+)
+
+// BenchmarkApplyQueryMappings benchmarks the optimized ApplyQueryMappings method
+func BenchmarkApplyQueryMappings(b *testing.B) {
+	// Setup test data
+	mappingList := config.MappingList{
+		ID:       "test-mapper",
+		FoundryA: "opennlp",
+		LayerA:   "p",
+		FoundryB: "tt",
+		LayerB:   "p",
+		Mappings: []config.MappingRule{
+			"[PIAT] <> [PDAT]",
+			"[PPER & opennlp/m=PronType:Prs] <> [PPER]",
+			"[PRELS] <> [PRELAT]",
+			"[PIDAT] <> [PDAT]",
+			"[DET & opennlp/m=AdjType:Pdt] <> [ART]",
+			"[DET & opennlp/m=PronType:Ind] <> [PIS]",
+		},
+	}
+
+	mapper, err := NewMapper([]config.MappingList{mappingList})
+	if err != nil {
+		b.Fatalf("Failed to create mapper: %v", err)
+	}
+
+	// Test cases that represent different scenarios
+	testCases := []struct {
+		name string
+		data map[string]any
+		opts MappingOptions
+	}{
+		{
+			name: "Simple_term_match",
+			data: map[string]any{
+				"@type":   "koral:term",
+				"foundry": "opennlp",
+				"key":     "PIAT",
+				"layer":   "p",
+				"match":   "match:eq",
+			},
+			opts: MappingOptions{Direction: true},
+		},
+		{
+			name: "Complex_term_group_with_match",
+			data: map[string]any{
+				"@type": "koral:termGroup",
+				"operands": []any{
+					map[string]any{
+						"@type":   "koral:term",
+						"foundry": "opennlp",
+						"key":     "DET",
+						"layer":   "p",
+						"match":   "match:eq",
+					},
+					map[string]any{
+						"@type":   "koral:term",
+						"foundry": "opennlp",
+						"key":     "AdjType",
+						"layer":   "m",
+						"match":   "match:eq",
+						"value":   "Pdt",
+					},
+				},
+				"relation": "relation:and",
+			},
+			opts: MappingOptions{Direction: true},
+		},
+		{
+			name: "No_match_scenario",
+			data: map[string]any{
+				"@type":   "koral:term",
+				"foundry": "opennlp",
+				"key":     "NOMATCH",
+				"layer":   "p",
+				"match":   "match:eq",
+			},
+			opts: MappingOptions{Direction: true},
+		},
+		{
+			name: "With_foundry_override",
+			data: map[string]any{
+				"@type":   "koral:term",
+				"foundry": "opennlp",
+				"key":     "PIAT",
+				"layer":   "p",
+				"match":   "match:eq",
+			},
+			opts: MappingOptions{
+				Direction: true,
+				FoundryB:  "custom",
+				LayerB:    "pos",
+			},
+		},
+		{
+			name: "Nested_token_structure",
+			data: map[string]any{
+				"@type": "koral:token",
+				"wrap": map[string]any{
+					"@type": "koral:termGroup",
+					"operands": []any{
+						map[string]any{
+							"@type":   "koral:term",
+							"foundry": "opennlp",
+							"key":     "PPER",
+							"layer":   "p",
+							"match":   "match:eq",
+						},
+						map[string]any{
+							"@type":   "koral:term",
+							"foundry": "opennlp",
+							"key":     "PronType",
+							"layer":   "m",
+							"match":   "match:eq",
+							"value":   "Prs",
+						},
+					},
+					"relation": "relation:and",
+				},
+			},
+			opts: MappingOptions{Direction: true, AddRewrites: true},
+		},
+	}
+
+	// Run benchmarks for each test case
+	for _, tc := range testCases {
+		b.Run(tc.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				_, err := mapper.ApplyQueryMappings("test-mapper", tc.opts, tc.data)
+				if err != nil {
+					b.Fatalf("ApplyQueryMappings failed: %v", err)
+				}
+			}
+		})
+	}
+}
+
+// BenchmarkApplyQueryMappingsWorstCase benchmarks the worst case scenario
+// where we have many rules but no matches (tests optimization effectiveness)
+func BenchmarkApplyQueryMappingsWorstCase(b *testing.B) {
+	// Create a mapper with many rules
+	manyRules := make([]config.MappingRule, 100)
+	for i := 0; i < 100; i++ {
+		ruleChar := string(rune('A' + i%26))
+		manyRules[i] = config.MappingRule("[UNUSED" + ruleChar + "] <> [TARGET" + ruleChar + "]")
+	}
+
+	mappingList := config.MappingList{
+		ID:       "many-rules",
+		FoundryA: "opennlp",
+		LayerA:   "p",
+		FoundryB: "tt",
+		LayerB:   "p",
+		Mappings: manyRules,
+	}
+
+	mapper, err := NewMapper([]config.MappingList{mappingList})
+	if err != nil {
+		b.Fatalf("Failed to create mapper: %v", err)
+	}
+
+	// Test data that won't match any rule
+	testData := map[string]any{
+		"@type":   "koral:term",
+		"foundry": "opennlp",
+		"key":     "NOMATCH",
+		"layer":   "p",
+		"match":   "match:eq",
+	}
+
+	opts := MappingOptions{Direction: true}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, err := mapper.ApplyQueryMappings("many-rules", opts, testData)
+		if err != nil {
+			b.Fatalf("ApplyQueryMappings failed: %v", err)
+		}
+	}
+}