Very Low Framerate in Walking Dead Ep 4

I have been playing Walking Dead on Steam since launch and have had no graphics issues or slowdown until last night when I downloaded episode 4. The mouse moves very slowly on the title screen and when I started episode 4 the game was so stuttery that I couldn't even select a response to the first dialogue choice before time ran out! I turned on FRAPS to see what the framerate was and it said 15-20 FPS on the title screen! I set all of the graphics options to the lowest settings and the FPS only increased to 25-30, still on just the title screen. The game itself is unplayable. My computer specs are:

i5 CPU
Windows 7 32bit
4G ram
Radeon 6850

My video card drivers are up to date.
Again, the game ran perfectly smooth and stable before the update yesterday.