I have this weird problem. My Macbook Pro 13 retina is just a couple of months old. For some reason (and at some point) the login screen started to lag like crazy. It's like it's "choppy". If I move the mouse it kinda moves for a bit and then stops for a second and move again. Same goes for the keyboard. That's it. But as soon as I've typed in my password and hit login everything seems to run as normal. Maybe I oughta make a video to demonstrate this. Any ideas what might cause this? I've been googling but haven't found anyone describing the exact same problem, and no solution so far. I'm using yosemite and it's a 2,4 ghz i5 with 8 gb ram and a ssd drive.