A collision issue possibly. There are several objects that do this as well. Hopefully it will be fixed at some point
Generally with objects you can alter the collision settings to a less demanding collision type, so you may well be able to do this with the characters also. Try changing collision type to 21 in the FPE.
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.
