There's a broken stone platform area you have to make a few jumps on withing BFD, with the last jump being especially difficult if you've got low fps. It's even easy to miss the jump with smooth frames. I remember trying to help a friend get across it, but his old Athlon XP / 512MB / 9200 Radeon machine was choking fps there. After about 30 minutes of trying to make that jump, he hearthed out.