# CPython experimental JIT

13 Hacker News commenters recommended CPython experimental JIT and 16 criticized it, November 2025 to November 2026. It was recommended in 3 of 13 months.

**Verdict:** Opt-in JIT compiler in CPython 3.15 that some people credit with real speedups, mostly on toy benchmarks. Critics say the gains are too small to justify its complexity.

## Why people recommend it

- Real speedups in Python 3.15 (3 comments): "Good news. Python 3.15 adapts Pypy tracing approach to JIT and there are real performance gains now" ([source](https://news.ycombinator.com/item?id=47376224)) "The experimental JIT was reported to finally breaking even and surpassing the default interpreter" ([source](https://news.ycombinator.com/item?id=48426591)) "the JIT is around 100% faster for toy programs like Richards" ([source](https://news.ycombinator.com/item?id=47377623))
- Technically exciting, worth keeping on main (3 comments): "They belong on main because new optimizations and heuristics will always be generated." ([source](https://news.ycombinator.com/item?id=50259825)) "It's unfortunate that a technically exciting new feature is being killed" ([source](https://news.ycombinator.com/item?id=50257972)) "Why not keep the JIT and let it evolve alongside the new framework?" ([source](https://news.ycombinator.com/item?id=48412519))

## What people warn about

- Project pulled or stalled upstream (5 comments): "Kind of a shit move to suddenly pull the rug once they've finally gotten it working." ([source](https://news.ycombinator.com/item?id=48426857)) "Seeing all of that get bogged down in committee bureaucracy now is just frustrating." ([source](https://news.ycombinator.com/item?id=50257957)) "Now the new JIT is dying because of what seems to be a lack of upstream interest." ([source](https://news.ycombinator.com/item?id=50258188))
- Gains too small for complexity (4 comments): "it's still only 15% faster than a simpler alternative. In a language that is 50x slower than the alternatives. Clearly not worth it." ([source](https://news.ycombinator.com/item?id=48428208)) "Complicating the code base for occasional 50% speedups just isn't worth it." ([source](https://news.ycombinator.com/item?id=48427108)) "best case 15% faster clearly isn't worth the complexity of a JIT" ([source](https://news.ycombinator.com/item?id=48427204))
- Little measurable speedup overall (4 comments): "the CPython JIT finally managed in 3.15 to be ~5% faster than the stock interpreter on x86_64" ([source](https://news.ycombinator.com/item?id=47846383)) "The CPython JIT has barely had any impact on its performance." ([source](https://news.ycombinator.com/item?id=48067321)) "the performance of the JIT was always fairly underwhelming" ([source](https://news.ycombinator.com/item?id=50258331))
- Better served by PyPy or YJIT (2 comments): "While this is great, I expected faster CPython to eventually culminate into what YJIT for Ruby is." ([source](https://news.ycombinator.com/item?id=47376514)) "Perhaps if the money which was spent on the built-in JIT had been spent on PyPy we'd be somewhere." ([source](https://news.ycombinator.com/item?id=50270555))

## Alternatives hackers recommend

- [Numba](https://hackerapproved.com/p/numba.md): 30 recommend
- [YJIT](https://hackerapproved.com/p/yjit.md): 10 recommend
- [HotSpot JVM](https://hackerapproved.com/p/hotspot.md): 8 recommend
- [ZJIT](https://hackerapproved.com/p/zjit.md): 7 recommend
- [Mir JIT compiler library](https://hackerapproved.com/p/mir.md): 6 recommend

## Cite as

Hacker Approved, "CPython experimental JIT", https://hackerapproved.com/p/cpython-experimental-jit/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).