Blender on Second Monitor suddenly lags I run a 3 monitor setup. I'm on windows 7 with 3.4ghz quad core, 32gig RAM, Titan GTX, and 770. My primary monitor is on the Titan, and the secondary 2 monitors are on the 770. I have been used to running my 3D viewport on the main monitor, and a secondary window on the 2nd monitor (usually node editor) and then a web browser on the 3rd monitor.

My second monitor recently took a knock and started having problems, so I got a new one. The new monitor has become the primary monitor, and the previous primary monitor is now the 2nd monitor. And now, whenever I put a second blender window on the 2nd monitor, it lags horribly and is unusable. If I put it on the 3rd monitor, it works fine (but that monitor is small, so I don't want it there.) Other programs work fine on my 2nd monitor.

What can I do about this? Nothing else about my setup has changed. All drivers are up to date.

Update:
If I switch to a basic theme, the problem goes away. But why is this suddenly necessary when I never had this before?

Update 2:
I have noticed that monitor 3 runs things just fine with no lag. I vaguely remember in the past when I had a different 3 monitors with an older setup (had a 580 instead of Titan) I had the slowdown issue, but on monitor 3 instead of 2. Perhaps it is able to run 2 monitors without slowdown, and my resuffling of monitors means the poor performance is now on current monitor 2, when before it was on monitor 3?
I still don't know the answer to the overall issue, but I have found why this occurred for me specifically.

First, turning off Windows Aero (or doing anything that disables it) will solve this problem. With Aero on, it seems that I get normal performance on 2 of the 3 monitors. In the past, my web browsing monitor was the odd man out. After some flipping things around, I found that whichever monitor was plugged in second (out of 3) will be the one that has issues. So un plugging and re-plugging the screen I wanted good performance on solved the problem, even with Aero enabled.

There must be a lot of variables going on behind the scene that I don't understand, so if anyone ever figures that out I'll be happy to pick a new answer. But for now, this does shed some light on the situation.