I've not had problems watching films, but I don't get a lot of time recently for this, so it tends to be midnight-3am (I also skip the results that list a hosting company that is often slow, especially for HD films).
It could be worth trying a different build of XBMC (just in case it is a software issue) if clearing data and re-installing the add-ons doesn't improve matters (e-mail or start a live chat if you need a hand).
Another test would be to find a friend who has a different ISP, and take the DroidBOX to their place for one evening during peak times. If they get the same issue, then it is likely that the individual servers at the other end are suffering. If they don't get problems, it could be the routing used by your ISP. Not much you can do then other than swapping to the same ISP as your friend, but worth looking into.