1. Launch LibreCalc 5.2.0.1 2. Open the attachment from bug 100709 3. While the spreadsheet is opening (which takes a pretty long while), drag around two or more corners of the window to resize it. Notice how at some point, the resizing handler keeps firing with every mouse move. It could be argued this is a corner case, but it's not. After the resizing has stabilized, 4. Open another file (I could reproduce the issue with a CSV with less than 20 lines), 5. Resize that window after the file has finished loading (a very legitimate use case). You may see the very same CPU-killing behavior as seen at the end of the screencast. I've seen the second part (completely normal use case) of the bug many times, but it appears it takes working with Calc for a number of minutes before the issue appears. Steps 1-3 simply accelerate the reproduction.
Created attachment 126562 [details] LibreOffice extremely high CPU usage when resizing its window Adding the attachment separately because Bugzilla croaked when I added it along with creating the bug (it should've checked for the size being > 10,000Kb).
*** This bug has been marked as a duplicate of bug 99153 ***