diff --git a/tests/bench_includes_dense.cjs b/tests/bench_includes_dense.cjs
new file mode 100644
index 0000000..665447a
--- /dev/null
+++ b/tests/bench_includes_dense.cjs
@@ -0,0 +1,38 @@
+function runBench(label, fn, options) {
+  const warmup = options && options.warmup ? options.warmup : 5;
+  const samples = options && options.samples ? options.samples : 10;
+
+  for (let i = 0; i < warmup; i++) fn();
+
+  let min = Infinity;
+  let max = -Infinity;
+  let total = 0;
+  let last = 0;
+
+  for (let i = 0; i < samples; i++) {
+    const start = performance.now();
+    last = fn();
+    const elapsed = performance.now() - start;
+    if (elapsed < min) min = elapsed;
+    if (elapsed > max) max = elapsed;
+    total += elapsed;
+  }
+
+  console.log(label);
+  console.log(`  result: ${last}`);
+  console.log(`  mean: ${ (total / samples).toFixed(3) } ms`);
+  console.log(`  min: ${ min.toFixed(3) } ms`);
+  console.log(`  max: ${ max.toFixed(3) } ms`);
+}
+
+const arr = [];
+for (let i = 0; i < 1024; i++) arr.push(i);
+
+runBench("dense includes", () => {
+  let hits = 0;
+  for (let r = 0; r < 20000; r++) {
+    if (arr.includes(1023)) hits++;
+    if (arr.includes(-1)) hits++;
+  }
+  return hits;
+});
diff --git a/tests/bench_includes_generic_proxy.cjs b/tests/bench_includes_generic_proxy.cjs
new file mode 100644
index 0000000..4fae5dd
--- /dev/null
+++ b/tests/bench_includes_generic_proxy.cjs
@@ -0,0 +1,60 @@
+function runBench(label, fn, options) {
+  const warmup = options && options.warmup ? options.warmup : 5;
+  const samples = options && options.samples ? options.samples : 10;
+
+  for (let i = 0; i < warmup; i++) fn();
+
+  let min = Infinity;
+  let max = -Infinity;
+  let total = 0;
+  let last = 0;
+
+  for (let i = 0; i < samples; i++) {
+    const start = performance.now();
+    last = fn();
+    const elapsed = performance.now() - start;
+    if (elapsed < min) min = elapsed;
+    if (elapsed > max) max = elapsed;
+    total += elapsed;
+  }
+
+  console.log(label);
+  console.log(`  result: ${last}`);
+  console.log(`  mean: ${ (total / samples).toFixed(3) } ms`);
+  console.log(`  min: ${ min.toFixed(3) } ms`);
+  console.log(`  max: ${ max.toFixed(3) } ms`);
+}
+
+const generic = {
+  get length() {
+    return 1024;
+  },
+  get 1023() {
+    return 1;
+  }
+};
+
+const proxy = new Proxy(
+  { length: 4, 0: NaN, 1: 0, 2: NaN, 3: 1 },
+  {
+    get(target, key) {
+      return target[key];
+    }
+  }
+);
+
+runBench("generic array-like with getter", () => {
+  let hits = 0;
+  for (let r = 0; r < 20000; r++) {
+    if ([].includes.call(generic, 1, 1023)) hits++;
+  }
+  return hits;
+});
+
+runBench("proxy includes", () => {
+  let hits = 0;
+  for (let r = 0; r < 20000; r++) {
+    if (Array.prototype.includes.call(proxy, NaN, 1)) hits++;
+  }
+  return hits;
+});
diff --git a/tests/bench_includes_sparse.cjs b/tests/bench_includes_sparse.cjs
new file mode 100644
index 0000000..39c4c9d
--- /dev/null
+++ b/tests/bench_includes_sparse.cjs
@@ -0,0 +1,36 @@
+function runBench(label, fn, options) {
+  const warmup = options && options.warmup ? options.warmup : 5;
+  const samples = options && options.samples ? options.samples : 10;
+
+  for (let i = 0; i < warmup; i++) fn();
+
+  let min = Infinity;
+  let max = -Infinity;
+  let total = 0;
+  let last = 0;
+
+  for (let i = 0; i < samples; i++) {
+    const start = performance.now();
+    last = fn();
+    const elapsed = performance.now() - start;
+    if (elapsed < min) min = elapsed;
+    if (elapsed > max) max = elapsed;
+    total += elapsed;
+  }
+
+  console.log(label);
+  console.log(`  result: ${last}`);
+  console.log(`  mean: ${ (total / samples).toFixed(3) } ms`);
+  console.log(`  min: ${ min.toFixed(3) } ms`);
+  console.log(`  max: ${ max.toFixed(3) } ms`);
+}
+
+const arr = Array(1024);
+
+runBench("sparse includes(undefined)", () => {
+  let hits = 0;
+  for (let r = 0; r < 50000; r++) {
+    if (arr.includes(undefined)) hits++;
+  }
+  return hits;
+});