Global variables aren't shown because I forgot about them! Oops, will try to add in the next beta :)
Kurz - the "poly check/sec" is the number of actual collision polygon intersection tests that have been done. Usually the vast majority of collision checks can be immediately determined to be not overlapping since the object's bounding boxes do not overlap. This simple rectangle check involves a tiny amount of simple code, and is incredibly fast - you can easily have hundreds of them per tick and still get good performance. However if the object bounding boxes are overlapping, the engine then has to actually inspect the collision polygon lines, which is a bit slower (it currently has to check each line in the polygon, so slows down with more poly points). So basically it tells you how many collision checks are the full and slower check. Usually it's considerably less. For example the Ghost Shooter rain demo does about 140 collision checks per tick, but only 3-5 poly checks per tick - again a small enough number to barely impact performance at all. If poly checks read 100/tick, that might be cause for concern.