What is in theory possible in a language/runtime is often less important than historically contingent factors like which languages it’s easy to hire developers for that can achieve certain performance envelopes and which ecosystems have good tooling for micro-optimization.

In JS for example, if you can write your code as a tight loop operating on ArrayBuffer views you can achieve near C performance. But that’s only if you know what optimizations JS engines are good at and have a mental model how processors respond to memory access patterns, which very few JS developers will have. It’s still valid to note that idiomatic JS code for an arbitrary CPU-bound task is usually at least tens of times slower than idiomatic C.