New Minecraft snapshot make my Computer EXTRA laggy

Hi! I am having a problem with 14w05b not A, B.
I run an old, but fast mac laptop. The problem is that whenever I go to any of my worlds in 14w04b minecraft stalls for 10 to 30 second periods and the occur every 5 to 30 seconds, but in 14w05a I do not get any lag and stalls.

If you could Fix this bug I could enjoy the luxury of having the bug fixes of A and B!

You can't reproduce this bug unless you have a 2011 mac laptop that runs minecraft.