If your runtime is a JS interpreter, on iOS you’re almost always better off just using the OS’s interpreter (JSC). Your app will be smaller, and only the OS is

If your runtime is a JS interpreter, on iOS you’re almost always better off just using the OS’s interpreter (JSC). Your app will be smaller, and only the OS is allowed to do JIT so it will be much faster. Even without the JIT restriction, you wouldn’t be able to beat JSC as it’s one of the fastest runtimes out there, pretty much level with V8. Static Hermes sounds like a different prospect, though, if it’s able to use TS annotations to compile to mostly-static native code. That could be great for genuinely high-performance TS code. (Although you wouldn’t want to immediately shackle it to React Native...)