Low fps on secondary monitor

Hello all,

I have an issue while playing Diablo 3 on my secondary monitor. I like to run it windowed borderless so I can lookup gear on my primary monitor without alt-tabbing out of the game. The other day I noticed it dropped down to 30fps. To troubleshoot I usually go fullscreen to see if it isn't my gpu or something else is the issue. It bumps up to 60fps when I go fullscreen. A little messing around in windowed borderless and I noticed it jumps back up to 60fps when I move the taskbar to the monitor that is displaying the game. I tried moving the game to the other monitor and noticed the same behavior when moving the taskbar.

Anyone have any ideas why this is doing this? My drivers are up to date so this isn't the issue. I've never had to put the taskbar on the same monitor that displays the game before. I'm open to suggestion on how to troubleshoot the issue. I tried this on World of Warcraft and it has the same issue. 30fps when the taskbar is on the other screen and 60fps when I put it on the same monitor.

Here are my specs:

Mobo Asus p8z68

CPU 2600k slight OC to 4.0

Memory Vengence ddr3 1600 4x4gig

GPU EVGA gtx 760 atx

Dual monitor Dell u2412m w/ resolution of 1920x1200

OS Windows 7 Ultimate 64bit

SSD Plextor m5p Xtreme 256gb for OS and games

WD 500gb for storage