Comment by G3rn0ti

> How do you make LSPs fast?

https://github.com/blahgeek/emacs-lsp-booster

The fundamental issue is Emacs its JSON parser is currently still rather slow (not sure why actually). But in LSP mode it needs to parse the LSP server's many JSON response messages very quickly. The aforementioned booster converts all JSON into ELISP byte code so Emacs can process LSP messages much faster.

I guess, the Emacs project will have to tune their JSON parser in the future.