Well, it started yesterday, but suddenly zMud is a lot slower than usual, it even is stuck sometimes while I write, and then what I've written suddenly appears from nowhere.
And when I checked my system today, I saw that zMud suddenly takes around 30% to 52% of my cpu performance. And well, that's...not cool.

Does anyone know what could've affected that? I didn't install anything new, I didn't change any settings and my computer is pretty much above average too.

Try reinstalling it?

Did you install anything else after you installed it?

This usually happens in large multistate triggers or redundant if statements in aliases. The more zmud has to proccess at one time the slower it gets. When I first wrote my healing script for lusternia I wasn't caring about anything other than healing quickly, and so I would quite often end up seeing the first line of the fight, freezing, then seeing it all scroll passed me as the fight ended and zmud was done processing everything.

Use small multistate triggers, don't reparse more than you have to. Use folders which turn off and on instead, and try not to have your prompt trigger be a huge mess of if statements that end up being processed endlessly.

zMUD also has a flaw that they keep claiming is fixed, but I have never seen fixed, where it takes memory and doesn't return it unless you close zMUD and open it again, so if you get really bogged down you will end up needing to do that.

Also, depending on how badly you coded, Zmud might make a million extra variables that lags you to hell. Or it might make tons of duplicate variables, I would go through your variables and triggers to see, also make sure that all your multi-state triggers are reset.

Aye, I reinstalled it, and it ran smoother again, until I put my system up. After it was fixed, for example with turning folders on and off, it works a lot better now, though some of my customizations made it slower again.