Not all of these will boot, but most will. https://archive.org/details/softwarelibrary & https://archive.org/details/internetarcade
pspdfkit, unity, google earth, and figma spring to mind. Obviously more stuff is using it, but it isn't like there's a big index of sites using wasm.
> What kind of application needs more performance than Javascript can offer, but doesn't need full native performance?
Wasm and JS can achieve equal performance in modern browser engines (and note that in engines like v8, there are operations that can be reduced such that they compete with output from gcc and clang). The thing that wasm is designed to do is make that performance predictable. Optimizing JS requires a lot of guesswork which can end up incorrect, while wasm doesn't require any guesswork because it is strongly typed and uses a regular bytecode. Right now what is holding wasm back is coming up with all the best ways to reduce it to the machine code of the specific platform, and ways to reduce the performance hits of security checks wasm has. For example, v8 recently sped up wasm memory access by ~30% by getting rid of bounds checks and using mmap + sigsegv to detect out of bounds access.
I can see WASM becoming useful for enabling apps that do real-time audio/video/image processing in the browser. Games are another obvious use case.
Maybe one day I'll be able to run an Ableton-lite right in the browser.