Parsec has a DirectX 9 renderer for our client, which works on all versions of Windows 7 or greater. You should use the DirectX renderer if you're ever running into trouble with OpenGL. Unfortunately, the one downside of DirectX 9 is that VSync is forced on. We would love to support Directx 11, but that would cause issues for Windows 7 users.
You can change your renderer setting in the Parsec settings of your client here: