Finder Taking Up Too Much CPU

My girlfriend asked me to look at her old Mac Mini because it was running very slowly. Running the Activity Monitor showed the culprit: Finder. It turned out that Finder was taking up almost 90% of the CPU! Googling around showed that the Finder preferences could be corrupted, and deleting them should solve the problem. However it did no mention how to delete them, so I had to google a bit more. In the end I found the following page. The steps are quite simle.

1) Run the following command in the terminal:

rm ~/Library/Preferences/com.apple.finder.plist ~/Library/Preferences/com.apple.sidebarlists.plist

2) Log out and log back in.

3) Run the “Force Quit” application from the Apple menu in the top left corner.

4) Select Finder, and hit the “Relaunch” button.

5) ???

6) Profit!