This is happening to me too. i have 6 fps (highest) after the 1.5.8.2 update. I used to have around 20-25FPS normally but every once in a while it would drop to 10-15 FPS for a few seconds. Specs; CPU: AMD Athlon II X4 605e 2.3 GHz Ram: 6GB GPU: Nvidia GeForce GTX 560 Ti