diff --git a/benchmarks/completion.bench.ts b/benchmarks/completion.bench.ts
new file mode 100644
index 0000000..f0fbdfa
--- /dev/null
+++ b/benchmarks/completion.bench.ts
@@ -0,0 +1,79 @@
+import { Bench } from 'tinybench';
+import { RootCommand } from '../src/t';
+
+const bench = new Bench({ time: 1000 });
+
+const setupCompletion = () => {
+  const completion = new RootCommand();
+  completion.command('dev', 'Start dev server');
+  completion.command('build', 'Build project');
+  completion.command('test', 'Run tests');
+
+  completion.option('--config', 'Config file');
+  completion.option('--verbose', 'Verbose output');
+
+  const devCommand = completion.commands.get('dev')!;
+  devCommand.option('--port', 'Port number', function (complete) {
+    complete('3000', 'Development port');
+    complete('8080', 'Alternative port');
+  });
+
+  return completion;
+};
+
+const suppressOutput = (fn: () => void) => {
+  const originalLog = console.log;
+  console.log = () => {};
+  fn();
+  console.log = originalLog;
+};
+
+bench.add('command completion', () => {
+  const completion = setupCompletion();
+  suppressOutput(() => completion.parse(['d']));
+});
+
+bench.add('option completion', () => {
+  const completion = setupCompletion();
+  suppressOutput(() => completion.parse(['dev', '--p']));
+});
+
+bench.add('option value completion', () => {
+  const completion = setupCompletion();
+  suppressOutput(() => completion.parse(['dev', '--port', '']));
+});
+
+bench.add('no match', () => {
+  const completion = setupCompletion();
+  suppressOutput(() => completion.parse(['xyz']));
+});
+
+bench.add('large command set', () => {
+  const completion = new RootCommand();
+  for (let i = 0; i < 100; i++) {
+    completion.command(`cmd${i}`, `Command ${i}`);
+  }
+  suppressOutput(() => completion.parse(['cmd5']));
+});
+
+async function runBenchmarks() {
+  await bench.run();
+
+  console.table(
+    bench.tasks.map((task) => ({
+      name: task.name,
+      'ops/sec': task.result?.hz
+        ? Math.round(task.result.hz).toLocaleString()
+        : 'N/A',
+      'avg (ms)': task.result?.mean
+        ? (task.result.mean * 1000).toFixed(3)
+        : 'N/A',
+    }))
+  );
+}
+
+if (process.argv[1]?.endsWith('completion.bench.ts')) {
+  runBenchmarks().catch(console.error);
+}
+
+export { runBenchmarks };
diff --git a/package.json b/package.json
index b7b3b9f..065cfe3 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "build": "tsdown",
     "prepare": "pnpm build",
     "lint": "eslint src \"./*.ts\"",
-    "test-cli": "tsx bin/cli.ts"
+    "benchmark": "tsx benchmarks/completion.bench.ts"
   },
   "files": [
     "dist"
@@ -30,6 +30,7 @@
     "commander": "^13.1.0",
     "eslint-config-prettier": "^10.0.1",
     "prettier": "^3.5.2",
+    "tinybench": "^4.0.1",
     "tsdown": "^0.9.7",
     "tsx": "^4.19.1",
     "typescript": "^5.7.3",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 78da1d2..d963698 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -30,6 +30,9 @@ importers:
       prettier:
         specifier: ^3.5.2
         version: 3.5.2
+      tinybench:
+        specifier: ^4.0.1
+        version: 4.0.1
       tsdown:
         specifier: ^0.9.7
         version: 0.9.7(typescript@5.7.3)
@@ -1383,6 +1386,10 @@ packages:
   tinybench@2.9.0:
     resolution: {integrity: sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==}
 
+  tinybench@4.0.1:
+    resolution: {integrity: sha512-Nb1srn7dvzkVx0J5h1vq8f48e3TIcbrS7e/UfAI/cDSef/n8yLh4zsAEsFkfpw6auTY+ZaspEvam/xs8nMnotQ==}
+    engines: {node: '>=18.0.0'}
+
   tinyexec@0.3.1:
     resolution: {integrity: sha512-WiCJLEECkO18gwqIp6+hJg0//p23HXp4S+gGtAKu3mI2F2/sXC4FvHvXvB0zJVVaTPhx1/tOwdbRsa1sOBIKqQ==}
 
@@ -2708,6 +2715,8 @@ snapshots:
 
   tinybench@2.9.0: {}
 
+  tinybench@4.0.1: {}
+
   tinyexec@0.3.1: {}
 
   tinyexec@1.0.1: {}