Larian Studios Forums Divinity - Original Sin Divinity - Original Sin - Technical Issues Framerate drops as time goes by - game unplayable

If the support tool doesn't detect the install path you need to point it at the '..\SteamApps\common\Divinity - Original Sin' install folder (similarly for the GOG version). It automatically adds the '\Shipping\EoCApp.exe' part of the path to the program file, even if you browse to the shipping folder.