I'm certain that this community (and Tableau Support, as needed) can help you work through your performance issues.
I'll also point you to some materials which will help you understand Tableau's query generation, and you may discover other ways to express your filter criteria which aren't so expensive. The slides and video linked below are from our 2011 Tableau Customer Conference, and the talk is called "Tuning Tableau and Your Database for Great Performance". You can find it in the Advanced section here:
I hope this helps,
The pdf was helpful in highlighting where/how filtering impacts performance, which combined with a phone call with Tableau representatives steered me in the right direction towards possible optimizations.
Once I can set some time aside to review overall system optimization further, I'll absolutely be watching this video first to get some additional insights (haven't had a chance yet to watch more than the first few minutes).