1.2.1: Spawner FPS lag

[Elite29er_v2]

Version:
1.2.1

What is the bug:
When ever I place a skelly spawner from a diamond dolly into the nether, the frame rate drops to 0fps. Its only in the nether. Overworld is fine.

Mod & Version:
JABBA?

Paste.feed-the-beast.com log:


Can it be repeated:
Yes.

Known Fix:

 

[Trisscar]

I think this might have something to do with wither skeles in particular, a couple other people have posted issues with them.