Comment by kevincox

It surely depends on your use case. Testing my Ricochet Robots solver (https://ricochetrobots.kevincox.ca/) which is pure computation with effectively no IO the speed is basically indistinguishable. Some runs the WASM is faster sometimes the native is faster. On average the native is definitely faster but it is surprisingly within the noise.

Last time I compared (about 8 years ago) WASM was closer to double the runtime. So things have definitely improved. (I had to check a handful of times that I was compiling with the correct optimizations in both cases.)