# \[ANN\] Numba 0.66.0rc1 / llvmlite 0.48.0rc1 **URL:** \ **Category:** Announcements\ **Created:** [June 8, 2026, 7:05am UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250 "2026-06-08T07:05:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![esc](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/esc/32/49_2.png) [@esc](https://numba.discourse.group/u/esc)\ **Post date:** [June 8, 2026, 7:05am UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/1 "2026-06-08T07:05:06Z")
Hi all, I’m happy to announce fresh release candidates of Numba and llvmlite. Numba now upgrades to llvmlite 0.48 with LLVM 22 and restores `sys.monitoring` on Python 3.14.4 and later. Also, adds support for typed `set` containers and multi-dimensional fancy indexing. For more information about the state of the support and breaking changes for LLVM 22, please see: [LLVM 22 (llvmlite 0.48+) — llvmlite 0.48.0dev0+54.ge8d38ef.dirty documentation](https://llvmlite.readthedocs.io/en/latest/user-guide/llvm22.html) ## Numba 0.66.0rc1 **Install from [PyPI.org](http://PyPI.org):** ```bash pip install --pre numba==0.66.0rc1 ``` **Install from [anaconda.org](http://anaconda.org):** ```bash conda install -c numba numba=0.66.0rc1 ``` **Release notes:** - [0.66.0rc1](https://numba.readthedocs.io/en/0.66.0rc1/release/0.66.0-notes.html) ## llvmlite 0.48.0rc1 **Install from [PyPI.org](http://PyPI.org):** ```bash pip install --pre llvmlite==0.48.0rc1 ``` **Install from [anaconda.org](http://anaconda.org):** ```bash conda install -c numba llvmlite=0.48.0rc1 ``` **Release notes:** [v0.48.0rc1](https://llvmlite.readthedocs.io/en/v0.48.0rc1/release-notes.html#v0-48-0rc1-june-4-2026) Thank you again to all contributors for making this possible. ping [@RC\_Testers](https://numba.discourse.group/groups/rc_testers) ---
**Author:** ![seanlaw](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/seanlaw/32/506_2.png) [@seanlaw](https://numba.discourse.group/u/seanlaw)\ **Post date:** [June 8, 2026, 12:33pm UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/2 "2026-06-08T12:33:05Z")
All tests are passing for STUMPY: > ---
**Author:** ![yangeorget](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/yangeorget/32/1127_2.png) [@yangeorget](https://numba.discourse.group/u/yangeorget)\ **Post date:** [June 9, 2026, 6:40am UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/3 "2026-06-09T06:40:01Z")
Hello, I run a quick test with NuCS ([GitHub - yangeorget/nucs: NuCS is a Python constraint programming library for solving Constraint Satisfaction and Optimization Problems over finite domains · GitHub](https://github.com/yangeorget/nucs)) and my test suite runs three times slower!!! Is this expected ? Regards, Yan Georget ---
**Author:** ![swap357](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/swap357/32/1207_2.png) [@swap357](https://numba.discourse.group/u/swap357)\ **Post date:** [June 9, 2026, 11:09pm UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/4 "2026-06-09T23:09:20Z")
Thanks for reporting this! I was able to trace this to regression on [slice assignment](https://github.com/yangeorget/nucs/blob/062d11ba7c3b502138308a5e694d5bf026b80323/nucs/solvers/bound_consistency_algorithm.py#L149). I’ve created an issue on the tracker - [Performance regression on `0.66.0rc1` slice assignment · Issue #10643 · numba/numba · GitHub](https://github.com/numba/numba/issues/10643). This will need some more investigating for a proper fix. ---
**Author:** ![yangeorget](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/yangeorget/32/1127_2.png) [@yangeorget](https://numba.discourse.group/u/yangeorget)\ **Post date:** [June 10, 2026, 7:40am UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/5 "2026-06-10T07:40:02Z")
Thank you for this in-depth investigation! ---
**Author:** ![milton](https://avatars.discourse-cdn.com/v4/letter/m/87869e/32.png) [@milton](https://numba.discourse.group/u/milton)\ **Post date:** [June 13, 2026, 11:26am UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/6 "2026-06-13T11:26:30Z")
Thanks, looks good on [numbox](https://github.com/Goykhman/numbox/actions/runs/27464698335/job/81184826419), haven’t noticed any significant performance changes in tests relative to 0.65.1. ---
**Author:** ![sklam](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/sklam/32/9_2.png) [@sklam](https://numba.discourse.group/u/sklam)\ **Post date:** [June 17, 2026, 6:31pm UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/7 "2026-06-17T18:31:04Z")
[Update] A RC2 is posted for Numba > [@\[ANN\] Numba 0.66.0rc2](https://numba.discourse.group/t/ann-numba-0-66-0rc2/3252): > > The following issues were addressed in the Numba 0.66.0rc2 release: np.mean numerical issue: [`np.mean` on float32 arrays larger than 2^24 elements diverge from NumPy · Issue #10647 · numba/numba · GitHub](https://github.com/numba/numba/issues/10647) slice performance regression: [Performance regression on `0.66.0rc1` slice assignment · Issue #10643 · numba/numba · GitHub](https://github.com/numba/numba/issues/10643) Install from [PyPI.org](http://pypi.org/): pip install --pre numba==0.66.0rc2 Install from [anaconda.org](http://anaconda.org/): conda install -c numba numba=0.66.0rc2 Release notes: [0.66.0rc2](https://numba.readthedocs.io/en/0.66.0rc2/release/0.66.0-notes.html) No changes to … ---
**Author:** ![swap357](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/swap357/32/1207_2.png) [@swap357](https://numba.discourse.group/u/swap357)\ **Post date:** [June 23, 2026, 4:28pm UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/8 "2026-06-23T16:28:24Z")
Hi @yangeorget , The `0.66.0rc2` should have fixed performance regression on slice assignment and better yet improved it than what it was before the regression. If possible, could you check the NuCS test suite with the new rc to confirm ? ---
**Author:** ![yangeorget](https://yyz2.discourse-cdn.com/free1/user_avatar/numba.discourse.group/yangeorget/32/1127_2.png) [@yangeorget](https://numba.discourse.group/u/yangeorget)\ **Post date:** [June 23, 2026, 5:18pm UTC](https://numba.discourse.group/t/ann-numba-0-66-0rc1-llvmlite-0-48-0rc1/3250/9 "2026-06-23T17:18:57Z")
I confirm. Thanks for the fix.