If you have stuttering audio & video and / or massive slowdowns in the PC version of GRID Autosport here is a solution that MIGHT help if you´re running AMD / ATI hardware.
1.) Download the latest AMD catalyst drivers from here: http://support.amd.com/en-us/download (at the date of this post 14.4) but DO NOT install them at this moment
2.) Download the AMD Catalyst uninstall utility: http://support.amd.com/de-de/download/catalyst-uninstall-utility but DO NOT run it at this moment
3.) Go to Control Panel => Programs => Programs and Features and look for the AMD Catalyst Install Manager
4.) Click change and then select “Uninstall all AMD components” (Attention: this will remove all amd based drivers (graphics, chipset, etc.))
5.) Reboot your pc
6.) Windows will now install a leagcy graphics driver (things look very messy and very low resolution) or it will install an older version of the catalyst driver (which may be one reason for the grid problems)
7.) Start the AMD Catalyst uninstall utility from step 2 and let it remove all old drivers
8.) Reboot your pc
9.) If your desktop resolution wasn´t already messed up in step 6 it should do so now
10.) Install the AMD catalyst drivers from step 1
11.) Enjoy Grid Autosport without stuttering 🙂