Pretty much the same here as potkettleblack. PoF and Met were the hardest for me, due to having to actually understand rather than learn.
Perf was a struggle to get to grips at first but all fell into place by the time of the exam. The key was understanding the drag/EAS and power/TAS curves, and deriving whatever was required from there.
Others sailed through those but struggle with the more numerate subjects like Gen Nav and Mass & Balance. We're all different!