Have a look at the "What's new in Qlikview 11" Demo QVW.
In the Report tab you see a good way of handling your question.
Hope that helps,
As you've said your question is aboout performance, then I will suggest you use container as there is not calculation involve which might make it more quicker (optimised) compared to conditional show which has to calculate before show (not that this will make any massive difference, but little bit slower to container).
Hopeful this helps