perf: investigate native engine incremental rebuild regression in v3.9.1 #882
Description
Summary
The v3.9.1 incremental benchmarks show a notable regression in the native engine's incremental rebuild performance:
- No-op rebuild: 6ms -> 15ms (+150%)
- 1-file rebuild: 527ms -> 757ms (+44%)
- Native 1-file rebuild (757ms) is now 25% slower than WASM (603ms), reversing the typical parity
Full build improved 20% (6.5s -> 5.2s), so this appears specific to the incremental code path.
Context
Flagged by Greptile review on #879. The benchmark data is correctly recorded; this issue tracks investigating the root cause.
Investigation areas
- Check what changed in
crates/codegraph-core/between v3.9.0 and v3.9.1 that touches incremental/hashing paths - Check if the import resolution speedup ratio drop (2.1x -> 1.7x) is related
- Reproduce locally with
npm run benchmark:incremental