I am also experiencing this problem on my rMBP 2012.
However, I've also noticed that, as of 10.10.1, my rMBP is no longer using the integrated graphics. I've checked that "automatic graphics switching" is enabled, I've reset both the SMC and the PRAM, and no matter what I'm doing, my rMBP always seems to be using the discreet graphics card, even when I've just booted the computer and haven't yet opened a program.
I also checked in Activity Monitor to see if any running applications were requiring the "High Performance Graphics", and none of them do. So I'm not sure why my rMBP is choosing not to use the integrated graphics anymore...
I know it was switching between them in Mavericks, and I'm almost positive it was switching correctly with 10.10 (although 10.10 was when I started seeing the various other graphic artifacts and freezing issues discussed in this thread). It seems like, with the 10.10.1 update, something has changed that no longer allows my computer to use the integrated HD4000 Intel graphics.