How's the performance on the immutable vectors? I wrote an immutable vector library once, but it turned out impractical to do game physics with because it was

How's the performance on the immutable vectors? I wrote an immutable vector library once, but it turned out impractical to do game physics with because it was too slow. Switching to self-modifying vectors fixed the problem. I think the performance hit of allocating new JS objects might be too high for games.