diff --git a/benchmarks/warn.js b/benchmarks/warn.js
new file mode 100644
index 0000000..8a191b4
--- /dev/null
+++ b/benchmarks/warn.js
@@ -0,0 +1,17 @@
+'use strict'
+
+const { Suite } = require('benchmark')
+const warning = require('..')()
+
+warning.create('FastifyWarning', 'FST_ERROR_CODE_1', 'message')
+warning.create('FastifyWarning', 'FST_ERROR_CODE_2', 'message')
+warning.create('FastifyWarning', 'FST_ERROR_CODE_3', 'message')
+new Suite()
+  .add('warn', function () {
+    warning.emit('FST_ERROR_CODE_1')
+    warning.emit('FST_ERROR_CODE_3')
+  })
+  .on('cycle', function (event) {
+    console.log(String(event.target))
+  })
+  .run()
diff --git a/index.js b/index.js
index d0f0b6b..db43642 100644
--- a/index.js
+++ b/index.js
@@ -44,8 +44,8 @@ function build () {
   }
 
   function emit (code, a, b, c) {
-    if (codes[code] === undefined) throw new Error(`The code '${code}' does not exist`)
     if (emitted.get(code) === true) return
+    if (codes[code] === undefined) throw new Error(`The code '${code}' does not exist`)
     emitted.set(code, true)
 
     const warning = codes[code](a, b, c)
diff --git a/package.json b/package.json
index 0e922b4..b77ae24 100644
--- a/package.json
+++ b/package.json
@@ -31,6 +31,7 @@
   },
   "homepage": "https://github.com/fastify/fastify-warning#readme",
   "devDependencies": {
+    "benchmark": "^2.1.4",
     "jest": "^29.0.1",
     "standard": "^17.0.0",
     "tap": "^16.3.0",