The Mozilla SpiderMonkey team has made significant improvements to the Ion compiler backend, leading to a 75x increase in performance when compiling WebAssembly code. The optimizations address issues with excessive memory and CPU usage, particularly with large Wasm modules like Adobe Photoshop demos. Changes include switching from linked lists to vectors for register allocation, implementing a more efficient dominator tree building algorithm, and optimizing sparse bit sets. These improvements not only benefit the ONNX Runtime module but also other WebAssembly modules.

Source: https://spidermonkey.dev/blog/2024/10/16/75x-faster-optimizing-the-ion-compiler-backend.html