2nd vote for C++ tagging performance improvements. I have used every version of SlickEdit since about V9. V16 when used with large projects has me constantly trying to tweek and tune the settings to make projects not pause, freeze (the entire slickedit app until I need to kill it) or fail to find symbols. I used to like having colleagues in my office while I showed them some piece of code using slickedit -- now I usually cringe at the thought of navigating through my projects using slickedit for fear that it will lockup somehow while trying to find something.
I still really like slickedit because, when it works, I'm able to figure out how some code is called/structured way faster than my colleagues.