GC implementations over Wasm definitely have perf issues. eg. Go compiled to Wasm has these with its GC. The main way when compiling to Wasm now is to not use a GC, which is reasonable depending on the application in question. It's quite reasonable for games or graphics applications.

But yeah Wasm has definitely been used successfully with performance results in production, eg. in Figma: https://www.figma.com/blog/webassembly-cut-figmas-load-time-...