Two questions about your situation.

1. How old is your computer? Does it have a decent amount of both processor speed and RAM?
2. How large are the files that you have open that are giving you lag?

I am nowhere near a power user as I use only emacs for Org-Mode but even with a few of my insanely large PIM files (BookNotes.org which contains the notes and highlights to every every nonfiction books I have read in the last 10+ years) I have never encountered any lag in emacs.

Unless the package is a mode that’s actually active, I can’t see why packages would cause input lag.

I’ve noticed I have a lot of latency right after startup and the thing which seems to help is a manual garbage collect. That’s bit odd because the last thing I do in my config is set a 5 second timer which is fed a lambda to run a gc after the timer expires. Regardless, I still have better results if I run the gc manually.

I do load of metric ass ton of packages (and modes) and I recursively parse my Org/Org Roam directory for org-agenda items so I’m doing a lot of questionable things.

As others have said, sounds like we might both benefit by spending some quality time with the profiler.

I had some latency and stuttering after 29 I started using gcmh and it works much better. Hopefully that will help you

flyspell on large org-file give serious input lag