Fiber speed variations

We've had Sky Fiber at ours now for about 4/5 months. And things have been going pretty smoothly. Got it mainly to increase the speed of downloads, which has gone up significantly. Today I noticed something kind of strange though. While I was downloading an update for a game through the game itself I noticed that at it's peak it was downloading at just over 8mb/s, whereas when I've downloaded films for e.g. using a torrent client I've gotten just over 4 at the most. I'm guessing maybe this is due to the fact that the download for the game update was more direct, rather than possibly going through other parties which may be the case with torrent files. But I'm still surprised that the difference is so much. Anyone have any idea what the exact reason is?