Unpacking Cloudflare Workers CPU Performance Benchmarks

On October 4, independent developer Theo Browne published benchmarks comparing Cloudflare Workers with Vercel, initially showing Cloudflare performing worse than Node.js on Vercel by as much as 3.5x on CPU-heavy tasks. Cloudflare’s team investigated and found a range of small problems, from tuning and library differences to test issues, and they fixed several problems, reporting that Workers are now on par with Vercel in most benchmarks, except for one based on Next.js where the gap remains.

They highlighted that the original benchmark did not reflect billable CPU usage and that the improvements have delivered about a 25% boost in V8 garbage collection tuning, with broader benefits to all Workers. The post also describes efforts to optimise OpenNext and related adapters, reducing unnecessary allocations and copies, and notes fixes such as upstreaming a V8 patch to speed up JSON[.]parse with revivers and improving stream handling to reduce buffering.

Finally, they acknowledge remaining work, including further scheduling improvements and collaboration with Next.js and React upstream, while emphasising that the changes are already live for all workers.