Just chipping in regarding this weird issue on my new mbp 15 with gt750m and 512gb ssd + mavericks 10.9.4. Earlier today I've spend more than an hour on the phone with the Apple Care person just to fix this random issue that occurred out of nowhere. After doing everything they told me to do including doing a system restore, and still cannot fix the problem, I just had to do my own research as the last option before sending it back to the Apple store for repair. Luckily I found this thread and followed the popular consensus solution for the problem by installing Autocad 2014 and opening it once. And what do you know, the screen tearing/lagging problem disappeared just like that.
I dunno what is the cause of the problem when at first I thought it was the gpu hardware problem. But weirdly enough, installing and opening the Autocad even just once seem to do the trick.
I will be calling the Apple Care again tomorrow and let them know this issue because this needs to be fixed asap before the upcoming Yosemite.