Chrome hasn't optimized wasm very well yet. Wasm isn't and never was meant for frontend. It's meant for crunching data and making it possible to use the thousands of C libs computers run on to have a safe and efficient execution environment that is not restrained by the host software having implimented that C lib directly.

For example there was this app in C# that would convert images into 512 color palette and use dithering to retain some quality. I made a version in the browser, but because of js being too slow it didn't work for large images. Thing is, mine was far safer and accessible than the C# program.