So here's the problem, my graphics card is completely fine for minecraft, it's the GTX 750 TI. I'm almost sure it's not my PC considering none of the earlier builds lagged and hit the 120 fps cap limit that I chose with no stutter. Now in 1.8, I can see some posts that other people are lagging when they didn't before. My problem is if I stand still my fps is fine but as soon as I start moving or turn my screen even after chunks are done loading my fps drops to 20. I've had the game for a long time and it has never done this. Even back in 2011 I had no problems with my older card.
What is your rendering depth set at? I'm at the default of 8 chunks, but I saw another article stating you should have 2Gb for 16 chunks and the author stated he preferred using 4Gb if running 16 to 32 chunks. Sound like you're having a low memory condition. My client was also dropping to the low teens in fps every time I moved.
I thought of that, and installed 64 bit, but it did not solve the problem. FPS will drop as low as 2 but will idle at 60 if I don't move.