Nice find, only 4.5x slower is nothing to sneeze at. I doubt that WASM is optimal for interpretation and you could probably gain another 2x through a bytecode compilation target optimized for interpreting.
If your WASM code doesn't change (isn't being downloaded at runtime from the Internet), then you could ahead-of-time compile it to native machine code (ARM/ARM64) and link it into your app.
It doesn't look like anyone's tried to do it for iOS but InNative has a compiler for Windows/Linux.
Mobile Safari may support WASM, but I think the GP is suggesting that a native iOS app would not be permitted to load, compile, and execute a WebAssembly module.
JavaScriptCore and JS running in a web page using WKWebView are both running in the same app process and do not support WASM since they cannot generate code (cannot write to executable memory pages).
SFSafariViewController does support WASM by executing in a separate more privileged process but interaction with the app is very limited.
But WKWebView is equivalent to running inside a browser, with no system access.
If JSCore allowed WASM JIT-ing, one could easily port WASI to iOS for full system access, and update iOS apps by downloading new wasm versions. Of course Apple won't do that citing __Insert__App__Store__excuse__here, but everyone knows it's because they want that sweet 30% cut, and that can only be effectively enforced with a tight chokehold on updates
