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How AST-grep Rewrote Tree-sitter in Rust and Made It 30% Faster

astgrep.com

July 26, 2026

16 min read

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48/100

Summary

ast-grep rewrote Tree-sitter's C core in Rust, resulting in a 30% increase in parser speed and a 22% improvement in overall performance for ast-grep. The new core enhances parsing efficiency and accelerates tree reading.

Key Takeaways

ast-grep rewrote Tree-sitter's C core in Rust, achieving a 30% increase in parsing speed and a 22% overall performance improvement for ast-grep.
The Rust implementation outperformed the original C version in all parsing and traversal benchmarks, with a throughput increase of up to 29.74%.
The new Rust core uses approximately 8 MiB more memory during ast-grep runs compared to the C version, peaking at 91.2 MiB on large datasets.
The rewritten Tree-sitter maintains compatibility with existing generated languages and parsers while removing unnecessary editor-specific features.

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Community Sentiment

Mixed

Positives

Implementing incremental parsing improved performance from 5ms to 400us for small edits, showcasing tree-sitter's potential in real-world applications.
The ability to easily distribute grammars through package managers is a game-changer for expanding ast-grep's capabilities.

Concerns

The removal of incremental old-tree reuse raises concerns that performance gains are achieved at the expense of practical usability in common scenarios.
Many commenters find the AI-generated nature of the article disappointing, questioning the authenticity and value of the content.