Massive Lag Spikes since 14w17a snapshot

Since the addition of new world generation options in the 14w17a snapshot I get massive lag spikes when trying to create a new world, or just playing normally. I used to be able to play all the snapshots before 14w17a at constant 60 fps and without any problems until said snapshot was released. I downloaded the snapshot and then the first thin I did was create a new world, I went into More World Options and then the game froze. I thought it was just a bug with the snapshot so I started playing on my test world with the slime blocks and every few seconds I would get massive frame drops, my fps would drop from 60 to 0-5. Even when I lowered my video setting the same would happen.
Please fix this, because I'm really looking forward to play the new snapshots with underwater temples and new mobs.