Minecraft FPS Drop

I played minecraft fine in 1.7.4/1.6 60 FPS constant but when I updated to the snapshots my FPS went down the drain its fine for 30secs when I change render distance
so if im on 2 chunks 17 FPS 16 chunks 17 FPS then It drops to 4 and I have to change render distance to fix this BTW this mostly happens on Servers