I do not have the issues that the OP is having, but I too feel that Sonoma is not as stable or as fast as previous macOS releases. This is aside from things that were never fixed from previous releases, and the 'features' that I think are useless or gimmicky or feel like downgrades (to me) as that is all subjective, of course.
While Sonoma is not running slow on my Macs (M2 Mac mini 24GB/1TB, and M2 MacBook Air 16GB/1TB), there is a laggy feeling here and there. It just doesn't feel as 'snappy' as Ventura does on my Macs that I've not upgraded yet.
For example, open Settings > Wallpaper, click on one of your wallpaper folders so that all the thumbnails are revealed, then minimize the settings app in this view using Stage Manager. See that very un-polished, un-Apple-like choppy and jittery descent as it minimizes. This happens on both my Macs.
By the way, Sonoma killed the 'Drift' screen saver on both these Macs during the upgrade process. I am not sure why, but it can't be a coincidence on two different modern macs. An upgrade never broke anything on my Macs before. I think this screen saver had to be selected at the time of the upgrades for this to happen. I will see if having another screensaver selected changes anything when I upgrade my other Macs.
These are not big issues of course, and I expect some new-release bugs that need to be ironed out with point releases, but we are up to .3 of a major macOS release now, and I am just not feeling that macOS fit, finish and smoothness that you expect from Apple. I am wondering if 'clean installs' would help in some of these cases, something I typically do after a couple of upgrades, even though I was always told that this is unnecessary with Macs (and I've been a Mac user since the 90s).