I bought my MBPr 13 a couple weeks ago and I was running Yosemite on it. I upgraded to El Capitan and things were smooth as silk. Yesterday I did a fresh install after creating an USB boot disk and things seem to not be as smooth as they were. I installed the OS while on battery power, could this have anything to do with it? Is the stutter because it's still a fresh install? Any insight would be really helpful.