DWM: ExclusiveModeFramerateThresholdPercent

ive been trying to find what this reg key for DWM does and have had no success.

Code:

HKLM\SOFTWARE\Microsoft\Windows\Dwm\ExtendedComposition\ExclusiveModeFramerateThresholdPercent

anyone know what "ExclusiveModeFramerateThresholdPercent" does?