How to speed up the Rust compiler in September 2026
4 hours ago
- Overall mean wall-time reduction of 4.57% from July to September 2026, with 555 of 629 benchmarks improving.
- Noah Lev achieved significant speed improvements in rustdoc, detailed in a separate post.
- Jakub Beránek enabled PGO for Clippy, resulting in up to 18% wall-time improvement.
- Upgrading LLVM to version 23 contributed a mean 1.2% wall-time reduction across benchmarks.
- Polonius, the new borrow checker, was enabled on Nightly; optimizations by Jack Huey reduced instruction counts by up to 5%.
- The new trait solver was also enabled on Nightly; multiple PRs reduced compile times for outlier crates by 15-50%.
- Contributor xmakro made several optimizations, including a 1.58% mean cycle count reduction and up to 6% instruction count reduction.
- Improvements to dataflow analysis, including a new CFG traversal algorithm, gave up to 30% wall-time reduction for cranelift-codegen.
- Increased default stack size by Chris Denton reduced instruction counts by up to 3%.
- Performance improvement PRs were so numerous that rollups containing multiple PRs were used to merge them efficiently.