Immer Performance Testing

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

Setup

Install dependencies (in this directory):
bash
```
yarn install
```
Build Immer first:
bash
```
yarn build-immer
```
Build the benchmark bundle:
bash
```
yarn build
```

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

bash

yarn build-with-latest

Usage

Running Benchmarks

To run the performance benchmarks:

bash

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

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

Analyzing CPU Profiles

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

bash

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

What's Included

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

Benchmark Versions

The benchmarks compare:

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

Key Features

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