That's certainly true and I hope I didn't give the impression that I thought this was a binary situation. It's just that code which runs in a JITed environment, particularly one like the browser JavaScript runtimes which aren't even versioned, has an even wider exposure to skew. Everything running on a multiprocess/user operating system is exposed to resource contention but e.g. your JavaScript code also has to worry about things like Chrome disabling optimizations anywhere you use try/catch.