This build is almost completely frozen/unresponsive for me. Loading my 200+ tabs on startup takes forever. Any UI action like switching to a different tab takes like a minute or more. Task manager reports only around 20% CPU use, and other apps are still responsive when Opera developer is not.
Exiting also takes a long time. After exiting I made sure all Opera instances in the task manager (details) were gone before starting Opera again. It was just as unresponsive after the second (and third) launch. So I had to give up on 131.0.5877.0.
Had to revert to developer build 131.0.5868.0 which is fine and responsive.