Game Breaking Freezeing - Mob Spawners

[Gk2011]

I am trying to do a Let's Play with Hexxit. Pretty much like everyone else is running to do right now but, I am encountering the most game breaking lag I have ever experienced. I turned my FRAPS off but, am still experiencing the issue. I am attempting to conquer a spider dungeuon I don't know exactly what it is called. Has spider spawners inside with stairs leading to a roof and has several layers underneath with 3 opening. Structure is made of mossy cobblestone.

The game runs fine when in peaceful. Turn to normal let the spawners try and spawn and, freeze......wait 10 seconds. Tick 1 Frame. Freeze......wait 10 seconds. 1 frame.

The game seems to completely freeze rather then my frame rate dropping to zero. I am assuming this cause it took me 20 seconds to die surrounded by 30 cave spiders...Also though I was not recording a had fraps on and frame rate just stoped moving altogether rather then drop to 0 and 1.

CPU - 6300 Vishira AMD 6-Core

Graphics - GTX 680

I also installed Optifine into the pack but, I doubt its the issue.

Ideas?