While not all of the 11 code has been optimized yet, the app is multi-threaded and 64 bit compatible so the vast majority of the feedback thus far has been that 11 significantly outperforms the 10.xx series. That said, since the code optimization is not 100% complete, there are a few functions that required more code development. 11.2 will be out in a few weeks so give that a try. The optimization should be close to complete for 11.3 (July/Aug) as well.
In case it's something in your set-up, it's always a good idea to contact our Support Dept directly and explain what you're seeing.