Python 3.15 JIT compiler hits performance goals early, achieving 11-12% speed boost on macOS AArch64 and 5-6% on Linux x86_64 after community-driven development rescued project from funding loss.

Python 3.15’s JIT is now back on track

Ken Jin's Blog 17 Mar 2026 (JIT performance as of 17 March (PST). Lower is better versus interpreter. Image credits to https://doesjitgobrrr.com/). Great news—we’ve hit our (very modest) performance goals for the CPython JIT over a year early for macOS AArch64, and a few months early for x86_64 Linux. The 3.15 alpha JIT is about 11-12% faster on macOS AArch64 than the tail calling interpreter, and 5-6% faster than the standard interpreter on x86_64 Linux. These numbers are geometric means and ar...