Have you tried the new native compilation system? I haven't worked on LaTeX documents specifically, but I did see a noticeable improvement in responsiveness across the board and a massive improvement in Elisp-heavy functionality like org-agenda.

I've used it on both Linux and macOS; for whatever reason, my Emacs has always been snappier on my Linux machine, and that's still true with native compilation, but now the macOS experience is also pretty solid.