I am always in high performance mode.  the only thing i will do is change the brightness of the screen when i am indoors.  I am completely stock with no mods or ruu.  the phone does get hot when charging and streaming music but not to what i consider excessive.  i will have to check the temp when i am outside for a while again.  I usually overclock all my tech and if things get to hot things start to breakdown.  my rez has been rock solid and I have never had a problem that would indicate my phone was overheating.  If anybody has a phone that starts acting weird from heat or the battery drains to quickly I would return it.  the only other thing I would recomend is do install carat.  It is a battery app made by the tech college in southern california.  That could help to indicate in something is constantly using your battery and therefore increasing the heat.
				
			