Trying to profile a real session running on my slower laptop today. Already found two things of interest:
1. Clutter isn't compressing touchpad swipe events, processing them one by one, taking almost 2 ms each.
2. Layout running during picking? Doesn't seem intended.
Also worked on making a COPR with Tracy-instrumented Mutter so others can record their performance problems too. I'll link that later, once someone else gives it a try and confirms that it works.