This directory contains performance testing tools for Immer, allowing you to benchmark different versions of Immer and analyze CPU profiles to identify performance bottlenecks.

1. Install dependencies (in this directory):

   yarn install

2. Build Immer first:

   yarn build-immer

3. Build the benchmark bundle:

   yarn build

Alternately, you can rebuild both Immer and the benchmarking script:

yarn build-with-latest

To run the performance benchmarks:

# Run basic benchmarks, with relative version speed comparisons
yarn benchmark

# Run the benchmarks, but also generate a CPU profile
yarn profile

After running yarn profile, you'll get a .cpuprofile file. To analyze it:

# Analyze the most recent profile
yarn analyze-profile your-profile.cpuprofile

• immutability-benchmarks.mjs: Main benchmark script comparing different Immer versions
• read-cpuprofile.js: Advanced CPU profile analyzer with sourcemap support
• rolldown.config.js: Bundler configuration that eliminates process.env overhead

The benchmarks compare:

• immer7-10: Historical Immer versions
• immer10Perf: Current development version (references ../dist)
• vanilla: Pure JavaScript implementations for baseline comparison

• Sourcemap support: CPU profile analysis includes original function names
• Version-aware analysis: Breaks down performance by Immer version
• Production bundling: Uses Rolldown to eliminate development overhead