My problem is that when a game is running in the foreground, in Full Screen mode, any applications on my second monitor (such as youtube videos, videos, not app specific) drop their frame-rate to about 2-3 FPS.

It seems like some sort of power management option that I can't track down. As far as I can tell, it's not due to the GPU not being able to keep up. For instance, my PC can play League of Legends at about 280FPS when the framerate is uncapped. If i cap it at 60FPS using the in-game option, it has no affect on the performance of the background app.

Summary
        Operating System
            Windows 8 Pro 64-bit
        CPU
            Intel Core i7 3820 @ 3.60GHz    42 °C
            Sandy Bridge-E 32nm Technology
        RAM
            12.0GB Triple-Channel DDR3 @ 533MHz (7-7-7-20)
        Motherboard
            Gigabyte Technology Co., Ltd. X79-UD3 (SOCKET 0)    37 °C
        Graphics
            DELL U2713HM (2560x1440@59Hz)
            DELL U2713HM (2560x1440@59Hz)
            1280MB NVIDIA GeForce GTX 570 (Gigabyte)    58 °C
        Hard Drives
            212GB Volume0 (RAID)
            1863GB Western Digital WDC WD20EARS-00MVWB0 (SATA)  36 °C
            1863GB Western Digital WDC WD20EARS-00MVWB0 (SATA)  34 °C
        Optical Drives
            No optical disk drives detected
        Audio
            ASUS Xonar Essence STX Audio Device
Operating System
    Windows 8 Pro 64-bit
    Computer type: Desktop
Graphics
    Monitor 1
        Name    DELL U2713HM on NVIDIA GeForce GTX 570
        Current Resolution  2560x1440 pixels
        Work Resolution 2560x1400 pixels
        State   Enabled, Output devices support
        Multiple displays   Extended, Secondary, Enabled
        Monitor Width   2560
        Monitor Height  1440
        Monitor BPP 32 bits per pixel
        Monitor Frequency   59 Hz
        Device  \\.\DISPLAY4\Monitor0
    Monitor 2
        Name    DELL U2713HM on NVIDIA GeForce GTX 570
        Current Resolution  2560x1440 pixels
        Work Resolution 2560x1400 pixels
        State   Enabled, Output devices support
        Multiple displays   Extended, Primary, Enabled
        Monitor Width   2560
        Monitor Height  1440
        Monitor BPP 32 bits per pixel
        Monitor Frequency   59 Hz
        Device  \\.\DISPLAY5\Monitor0
    NVIDIA GeForce GTX 570
        Manufacturer    NVIDIA
        Model   GeForce GTX 570
        GPU GF110
        Device ID   10DE-1086
        Revision    A2
        Subvendor   Gigabyte (1458)
        Series  GeForce GTX 500
        Current Performance Level   Level 3
        Current GPU Clock   845 MHz
        Current Memory Clock    1900 MHz
        Current Shader Clock    1690 MHz
        Voltage 0.988 V
        Technology  40 nm
        Die Size    520 mm²
        Release Date    Dec 07, 2010
        DirectX Support 11.0
        OpenGL Support  5.0
        Bus Interface   PCI Express x16
        Temperature 57 °C
        Driver version  9.18.13.2018
        BIOS Version    70.10.55.00.01
        ROPs    40
        Shaders 512 unified
        Memory Type GDDR5
        Memory  1280 MB
        Bus Width   64x5 (320 bit)
        Filtering Modes 16x Anisotropic
        Noise Level Moderate
        Max Power Draw  219 Watts
            Count of performance levels : 3
                    Level 1 - "Default"
                        GPU Clock   50 MHz
                        Memory Clock    135 MHz
                        Shader Clock    101 MHz
                    Level 2 - "2D Desktop"
                        GPU Clock   405 MHz
                        Memory Clock    324 MHz
                        Shader Clock    810 MHz
                    Level 3 - "3D Applications"
                        GPU Clock   845 MHz
                        Memory Clock    1900 MHz
                        Shader Clock    1690 MHz

Things I've tried:

1) Updating the graphics driver

2) Setting windows power mode to High Performance

3) Reset Nvidia Global Performance settings to default