> Emacs is still so much slower than Neovim, even in the case of launching and immediately quitting

I agree, but there's ways around it. On my machine the Emacs daemon is ready before I even log-in (lingering [^0]).

I think I only restart the daemon when I update emacs and its packages, and yeah, Emacs and Spacemacs are slow, but do not slow me down.

[^0]: https://wiki.archlinux.org/title/Systemd/User#Automatic_star...