It takes over 60 seconds before the Options dialog is responsive after selecting the "Options..." from the menu. It shows the popup window immediately but the window doesn't respond until after a long time. When it finally does respond there are no delays.
I've tried reverting to 4.2.0 just to see if it's a recent bug, and I've tried removing all settings from 'LOCAL'/qbittorrent and 'ROAMING'/qbittorrent resulting in no change (except having to set everything up again ofcourse).
I don't have any third party apps running that monitor or interact with windows or windows controls in any way.
I'm on Windows 10 x64 2004 build 19041