Measure speed and coverage
Where are the bottlenecks? VB Watch proFILEr lets you measure execution speed. See what procedures are the slowest ones, and which lines or loops are taking up most of the time. Or measure execution times before and after your enhancements.
Test coverage. Are you sure you tested all your code? VB Watch Profiler records your tests as you execute them. It shows you in red what procedures and lines are still untested.
Make sure you've tested all the Select Case branches and nested If..Then..Else's too.