Firefox Nightly Flips On New JIT "Warp" Code For Greater JavaScript Performance

Mozilla's SpiderMonkey JavaScript engine team have been working on a big update to their just-in-time compiler code. This big update called "Warp" is now enabled in the latest Firefox Nightly builds for offering big speed-ups.

Warp aims to improve the Firefox JavaScript performance by reducing the amount of internal type information that is tracked along with other optimizations. Warp can lead to greater responsiveness and faster page load speed. Numbers cited by Warm developers are normally in the 5~15% range.

As of yesterday, Firefox Nightly now enables Warp by default. The enabling in Firefox Nightly is seeing 20% faster load times for Win64 Google Docs, 13% faster for the Android Reddit SpeedIndex, 18% faster for PDFPaint, and other measurable improvements elsewhere.

More details via this thread. Nightly is currently tracking Firefox 83 and hopefully this more widespread testing goes well and will remain on for the official release. I'll be working on some fresh Firefox benchmarks shortly.