I have the same problem. This little freezing (or how should I call it?) can be found in Opera, Opera developer & Opera beta.
Switching between two and more opened tabs is like pain in the ass - it takes 2-5 seconds
Typing in addressbar - rewriting existing url, or typing some parameters in the url --> pain in the ass no.2 - takes too 2-5 seconds while I see first letter I typed.
Those problems will occur also on clean Opera install.
OS: Arch Linux x64