VRAM usage 85%? That's pretty high, are you playing at 1080p?
Try performing a clean install of the GPU drivers: http://www.guru3d.com/files-details/display-driver-uninstaller-download.html
You can also try older versions of the drivers if a clean install of the latest drivers won't work. A scan with Malwarebytes might also be a good idea: http://www.malwarebytes.org/