I installed Catalina on my old Macbook Pro (2015), and it’s been struggling ever since. I’m not sure why the fans are running non-stop, but they are. Even with very minimal usage, it’s like the thing is prepping to take off.
I’ve looked into Activity Monitor, done all the standard Apple tricks, no dice. I upgraded Alfred, thinking it might be an issue with Spotlight but no love. I’ve tried all manner of things, and still the fans just go go go.
From what I can tell, it’s definitely Spotlight given that mds and mds_stores are hogging up resources a lot. I’ve moved an incredible number of folders into the “Privacy” section so they won’t be indexed, but that hasn’t helped much. I thought this was a Time Machine issue at first, but it’s been a few days now and I was really hoping things would have settled down.
Best guess so far is one comment I saw suggested it might take up to a week for Spotlight to index. That seems excessive, but maybe? My last ditch fix would be to kill Spotlight and use Alfred as just a glorified shortcut app. We’ll see.