The "predictable performance" point applies not just to performance across browsers but also that you don't need to pay JIT warm-up costs. A while back, I ran some benchmarks on the same codebase in TypeScript and AssemblyScript and found that wasm was much faster than JS for short computations and often slower than JS when V8 is given multiple seconds to fully warm up the JIT:
So really, it depends a lot on the use case. In my case, it's often a short-lived node process that a user is directly waiting on, so compiling to wasm is probably useful. It also depends on what you're doing; some types of work (e.g. where you'd want careful memory management) are a lot harder for V8 to optimize from JS and can be expressed more nicely in AssemblyScript or another language that gives more memory flexibility.
For that, it looks like unless you're running the same js on a really huge dataset webassembly will win (going from the second speed test). Even when you're compiling 50MB of JS with that thing, Wasm is 5% slower than JS, and when you're compiling 500KB (more typical) it's 300% faster.
https://github.com/alangpierce/sucrase/issues/216
So really, it depends a lot on the use case. In my case, it's often a short-lived node process that a user is directly waiting on, so compiling to wasm is probably useful. It also depends on what you're doing; some types of work (e.g. where you'd want careful memory management) are a lot harder for V8 to optimize from JS and can be expressed more nicely in AssemblyScript or another language that gives more memory flexibility.