I was playing around with my Nokia Lumia 521 and I found a game on the app store that seemed fun, but once I downloaded it and opened it it was extremely slow. It would stutter, the game and audio would freeze and it was just unplayable. I decided to keep playing it for another minute and I've started noticing that a few parts of the game that were recently the slowest, start to speed up, soon the lag stopped completely and it became extremely fast and snappy. There's probably something behind this, or maybe my hardware is getting used to it, an answer would be nice.