My TF2 alt-tabs very slowly, and I figured it had started happening again because of an update, but then I realized I should check my launch options. I had -refresh 120 in my launch options, so I decided to remove it since I'd read before it doesn't matter and TF2 uses your desktop refresh rate. However, my game felt incredibly choppy and (presumably) was refreshing at 60Hz. Removing it did make my alt-tabbing instant though as it used to be.
I should also mention that when I'm simply moving my mouse on my desktop or scrolling up and down in a browser, it normally feels like it's at 60Hz, but switches between that and 120. Since TF2 supposedly uses desktop refresh rate, I'm assuming something is wrong with my graphics settings elsewhere.
Any ideas?
ASUS GTX570
BenQ XL2420T
FX8350