If you're facing weird effects or poor performance when working with #Emacs (or #orgmode) and you're having a customized setup:

One thing that may solve some issues is removing your elpa/melpa packages and let it install from scratch.

It might be a good idea not to mix up #melpa and #elpa packages as it might introduce broken dependencies with mismatching package versions.

I've had my learning yesterday and it cost me and unfortunately another expert half of the day to find out about my mistake(s).

Edit: I initiated a #WORG page for tips like that: https://orgmode.org/worg/org-performance.html