Thanks -- we use Emscripten/WASM mainly for running command-line compilers/assemblers (like cc65 and SDCC).
Right now the emulators are all in JavaScript (except for MAME) which makes integrating with the IDE's debugging tools a little easier. It's performant enough for now, since we only have 8-bit platforms at low clock speeds.
Integrating a C emulation library like https://github.com/floooh/chips should be doable, since it doesn't have any dependencies.
Which specific CPUs or applications that you emulate really take advantage of the performance boost that WASM provides?