I realise the first is a known issue in the release notes - that tabs don't always display the contents until you click them to update them, but I thought you might like to know that MacNN forums (very) often exhibit this problem, so if you are looking for a good test case for fixing it:
Another issue that isn't listed (afaict) is that some sites display oddly in tabs:
e.g.
www.railheaddesign.com:
e.g your very own OmniWeb tab where the omni badge is floating about a third of the way up the tab from the bottom (as indicated and which I am guessing is similar to the RH Design issue as the blank area at the bottom of that tab appears to be the same as that in the OmniWeb tab):
