Comment by perpil

This is very thorough, but I have a few things to add if you are using Node 22. I benchmarked Node 22 earlier this year using something similar to the light benchmark. https://speedrun.nobackspacecrew.com/blog/2025/07/21/the-fas...

I found that Node 22 had ~50ms slower coldstarts than Node 20. This is because the AWS Javascript V3 SDK loads the http request library which became much heavier in Node 22. This happens on the newly released Node 24 as well.

I recommend that if you are trying to benchmark coldstarts on Lambda, you measure latency from a client as well. The Init Duration in the logs doesn't include things like decrypting environment variables which adds ~20ms and other overhead like pulling the function code from S3. The impact of this manifests when comparing runtimes like llrt to Node, the Init Duration is faster than Node, but the E2E time from the client is actually closer because the llrt bundle size is 4-5MB larger than Node.