I tried running 1.8 and man, I couldn't move. I thought at first it was just taking time to populate the new world, or update an old world to the new 1.8. I finally started messing with the video settings and discovered two things:
1. Turn "Use VBOs" on
2. Turn "Use VSync" off
VBOs preload something (technical jargon here). VSync prevents your monitor from rendering before it's ready. That is what killed my gameplay. There's lots of complaints on the MC forums, thought I'd share my solution here.
50 credits
Acquired on 2 April 2014