We have since long a list of all known speed bottlenecks of the engine. You'll find it in the manual under "Engine-> Frame Rate".

I'm indeed not very happy when users post statements like "if/then kills the frame rate". Attempts to follow such "advices" by avoiding if/then results in some waste of time but no better frame rate. But maybe that user meant that in a different way. I can not read and correct every thread here. I just suggest to apply some common sense and take such advices with a grain of salt. I know the bottlenecks rather well, so if in doubt you can always ask on the 'Ask Conitec' forum.