Yosemite upgrade–continuous slow screen redraw I recently upgraded to Yosemite, and now my laptop has the following issue:

Each and every window (the AppStore, Chrome, etc) seems to be continuously and very slowly redrawn, to the point where I can see the screen go white, and then slowly be drawn back in from the bottom to the top.

The only time when I every encountered a similar issue was when, on Ubuntu, I upgraded and lost support for my graphics card. However, I have no idea how to navigate this issue on OS X.
I had this problem and I solved it by resetting the PRAM/NVRAM, which is done via:


Shut down your Mac.
Locate the following keys on the keyboard: Command (⌘), Option, P, and R. 
Turn on your Mac.
Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
Hold these keys until the computer restarts and you hear the startup sound for a second time.
Release the keys.