Several seconds sounds like an exaggeration, but it never seems anything but sluggish to me.
One UX delay that irritates me is the time it often takes between hitting Win+R and the run dialogue finally being ready for input. Regularly the first few characters of what I type after that ends up going to the app that originally had focus. That used to be instant, on much older kit.
I don't use Windows often enough to go out of my way to customize it, plus I know that the next update will probably undo everything anyway, but now I have to wait around multiple seconds for it to realize the files are not there. And it won't even remember it from one instance of explorer to the next, or try to check on those files without blocking the entire app's UI.
This shitshow also happens in the open / save as dialogs when called from other apps.
I've mostly used OS X and Linux the last 25 years, but have been forced to use Windows at work and recently on my gaming computer, so I'm not really defending Windows here. But honestly, I don't have any big problems with it. It works OK for the most part.
I cannot list any of the bugs I have had with Windows off the top of my head, but I can with linux. Driver issues, Pulse audio randomly playing static, updates breaking my system, fractional scaling not working, I could go on.
I strongly disagree with this. When I am forced to use windows, I am constantly fighting with it to not be obnoxious. It takes many seconds to do something as simple as bring up an explorer window. I can't count the number of times I have had to dig into menus to disable this or that ad panel or other bloatware. In linux, I occasionally have to figure out how something works and fix it, but there are generally many months between those events, when everything just works and gets out of my way.