diff --git a/README.md b/README.md
index 4bffac1..16c86d0 100644
--- a/README.md
+++ b/README.md
@@ -228,7 +228,24 @@ npm run update-rules
 npm run build
 ```
 
-Feel free to fork if you see possible improvements!
+## Benchmarking
+
+Compare ops/sec using local source vs _latest_ published version.
+
+```sh
+npm run benchmark
+```
+
+Compare to a specific version:
+
+```sh
+npm run benchmark -- v1.13.0
+```
+
+CAVEATS:
+
+* The benchmarking script only works on ESM (it uses [`vm.SourceTextModule`](https://nodejs.org/docs/latest-v20.x/api/vm.html#class-vmsourcetextmodule)),
+  so we can only compare to `v1.13.0` and above.
 
 ## Acknowledgements
 
diff --git a/benchmark/suite.js b/benchmark/suite.js
index 284301d..751c6e1 100644
--- a/benchmark/suite.js
+++ b/benchmark/suite.js
@@ -109,9 +109,7 @@ const fetchModule = async (version) => {
   return mod.namespace;
 };
 
-const main = async () => {
-  const compareToVersion = 'v1.13.0';
-
+const main = async (compareToVersion = 'latest') => {
   const results = await runSuites([
     { module: psl, version: 'source' },
     { module: await fetchModule(compareToVersion), version: compareToVersion },
@@ -120,7 +118,7 @@ const main = async () => {
   printResults(results, compareToVersion);
 };
 
-main().catch((error) => {
+main(process.argv[2]).catch((error) => {
   console.error(error);
   process.exit(1);
 });