The past 2 months (or so) my Mac Mini was becoming more and more slow. Very often I would get the “spinning beachball”. Also music playback in iTunes or movie playback in VLC suffered from stuttering.
After a while I noticed a blinking dot in the Spotlight icon. It turned out that Spotlight was indexing my TimeMachine disk. This indexing would never finish though! My Mac is almost always on because of online backup, so I expected it to finish sometime.
Excluding TimeMachine from Spotlight indexing (via Privacy settings) did not help. Rebooting did not help. Reformatting my TimeMachine backup disk did not help. Etc.
Finally, I found an article with a solution that worked for me: https://discussions.apple.com/thread/2741958?start=0&tstart=0
Search for the post by Pondini.
- Download Tinkertool to make hidden files visible in Finder
- Go to you TimeMachine disk
- Remove the Spotlight Index (.Spotlight-V100) folder
- Restart your machine
This worked for me. It started by recreating the index. Again it said it was indexing my TimeMachine disk, but now it actually calculated the remaining time. Now it is finished and my machine works like a charm.