I think you kinda missed the point, tbh. You don't need in place memory operations with ridiculous performance in most(tm) applications. On the contrary there

I think you kinda missed the point, tbh. You don't need in place memory operations with ridiculous performance in most(tm) applications. On the contrary there are many applications where security is far more important than speed and something that basically embodies remote code execution (browser) is one of those. The fact that JS has made this implementation choice while at the same time being mutable is the true peril, not the specific implementation per se.