[bzxcvbn]

I used to use Emacs (for 15+ years) with a handcrafted config. It didn't feel slow because of spacemacs, which didn't even exist when I started using it. It felt slow because anything that should have been async (pushing to git, asking the LSP server to do something, you named it: spell checking, etc.) would hang up the whole UI.

[d0mine]

There is no need to hang UI while communicating with external processes. There can be both sync and async interfaces (you don't even need threads, though they could be handy sometimes).

I use magit everyday and can't tell whether it sync or async (meaning no performance issues).

jupyter-python code blocks are definitely async (I can type in the same buffer while they are calculating something).

There is no issue with tailing logs in one vterm buffer and doing whatever in another.

Some operations are slow e.g., generating daily agenda from multi year org files (though it is not slow enough that I've bothered to do anything about it).

[seanw444]

Which it does have threading now, at least.