alt Hacker NewsIs Javascript significantly slower? It is extremely common in the real world and so a lot of effort has gone into optimizing it - v8 is very good. Yes C and Rust enable more optimizations: they will be slightly faster, but javascript has had a lot of effort put into making it run fast.
Replies
sgeisenh • yesterday at 2:05 PM
Yes, for most real-world examples JavaScript is significantly slower; JIT isn’t free and can be very sensitive to small code changes, you also have to consider the garbage collector.
Speed is also not the only metric, Rust and C enable much better control over memory usage. In general, it is easier to write a memory-efficient program in Rust or C than it is in JS.
Yes. V8 (and other Javascript JIT engines) are very good, with a lot of effort put into them by talented engineers. But there's a floor on performance imposed by the language's own semantics. Of course, if your program is I/O bound rather than CPU bound (especially at network-scale latencies), this may never be noticeable. But a Javascript program will use significantly more CPU, significantly more memory, and both CPU and memory usage will be significantly more variable and less predictable than a program written in C or Rust.