I added something to the Install Instructions of GT6:
For people with Graphics Lag, there are a few ways to maybe fix it: Change the Mipmap Settings, Reduce Render Distance, Disable VSync, Disable Smooth Lighting, increase RAM, install Fastcraft, install the right Version of Optifine for your System or delete the wrong Version of Optifine for your System.
The “delete the wrong Version of Optifine” Part specifically. The rest was already there.
And cant you just turn off VSync in the Minecraft Options?