VIM but particularly Emacs can get painfully slow on semi-large files (and forget about it if you have very long lines) and you have to tweak or disable lots of

VIM but particularly Emacs can get painfully slow on semi-large files (and forget about it if you have very long lines) and you have to tweak or disable lots of features if you want them to be reactive and not peg your CPU. So I think it's more down to the implementation than the language it's written in. V8 is really efficient at running JS, what slows it down is the 25 levels of abstraction and indirection that is usually added on top of it. OP claims to try to reduce that, so maybe give it a chance?