yes for me too.
However, it's less of a problem because I usually memorize the alt-tab (often switching once or twice) and it works even if the graphics haven't shown up yet.
And some of the developers weren't very friendly on the bugtracker so I didn't dare to 'mention' more than one problem in the same year.
For that reason, I am not sure if it's a lag bug or actually by design (so that the popup doesn't flash for a single alt-tab). Not that I agree with that, but illogical design choices is second nature to any linux project.