We had this problem with the original one x too, its due to the gpu clock being synchronized with the cpu clock. that means that if the cpu load it high, per say a tegrazone game like shadowgun, then the gpu scales up as well alowing for fluid gameplay even with detailed graphics. However this also means that when the cpu load is light, i.e temple run, the gpu will hardly scale at all implying that the phone will lag with simple games like doodle jump but not graphics heavy games like dead trigger. Games like asphalt 7 lag because the game probably only uses 1 or 2 core, thus the gpu is only at aroung %50 power. Hamdir found a way to run the gpu independently but we`ll have to wait for proper root and custom recovery for that.