Feed the beast fps drop (Minecraft)?

So in feed the beast i go from 80 fps to 2 for about 2 seconds then it goes back up then down again. Why is this happening i can run other games good without this problem. My friend does not have this problem only me. We play on a server when we first started it was good and i had no drop now 1 month in its doing this i never had this before please help what can i do. I tried to turn down settings like to the worst like tiny render distance and it still does it.

Specs
Intel Core i5-3210M @ 2.5 ghz
8 gb ram
AMD Radeon HD 7670M
Windows 8

Guest

By default Minecraft saves the map every two seconds, this could cause a spike if you have a slow hard-drive, this should only affect singleplayer though.

If it only happens when you are moving in a direction, it might also lagspike when new chunks are loaded and rendered into the game.

TRGWII