Well-optimized JavaScript can, if you jump through hoops like avoiding object creation and storing your data in `Uint8Array`s. But idiomatic, maintainable JS simply can't (except in microbenchmarks where allocations and memory layout aren't yet concerns).

In a game engine, you probably aren't recreating every game object from frame to frame. But in a compiler, you're creating new objects for every file you parse. That's a huge amount of work for the GC.