I have not been able to replicate the extreme battery consumption either. However, when it happens, the phone gets REALLY hot in the top left corner where the CPU/GPU is located. Hot as if I was charging and playing a 3D game at the same time. So most likely it is not a feature or combination thereof that makes this happen, but a freeze/looping.
SGS 2, stock 2.3.5
SGS 2, stock 2.3.5