LeanFPS is an MIT-licensed Windows 10/11 x64 game optimization utility built with Rust and egui/eframe. Its full source is available at https://github.com/Jamailar/leanfps. It detects supported games, offers per-game and genre profiles, measures average FPS and 1% lows through Windows event tracing, and records session history. Each setting has an explanation and an individual Undo option. Temporary session changes restore on exit; persistent system settings remain until individually undone.

The free edition includes core tweaks and FPS measurement. Optional Pro is currently US$19 as a one-time early-bird purchase. Results depend on the PC and game; no fixed FPS improvement is guaranteed. LeanFPS does not inject an overlay into games or disable Defender, Memory Integrity, the firewall or Windows Update.

The attached images are from the public LeanFPS website. Its illustrations explain features and use example values, not benchmark results.