The plants that create environmental surfaces seriously lag the game.
While some sections aren't so bad... The chest surrounded by zombie heads is particularly bad. So much so that me and my friend eventually just loaded the game and skipped that section even though we could have got the treasure.
Yeah, I've had serious problems with that too. I wonder if there might be a memory leak: the game certainly seemed to be consuming memory quite enthusiastically at that point and I had to kill it. That happened a couple of times.
