Chunk loading slower in 1.8.2-pre3 than in 1.8.1

Chunk loading in 1.8.2-pre1, -pre2, -pre3 seems to be much slower than in 1.8.1
The performance is comparable to 1.7.X versions and below.
Steps to reproduce:
1.Create a new world (you can see both default and superflat world types on the screenshots below) using 1.8 or 1.8.1 version.
2.Chunk loading is quite fast, isn't it?
3.Save and quit to title, then quit game.
4.Now launch 1.8.2-pre3 (affects pre2 and pre1 as well) version and enter the world.
5.Compare chunk loading speed in 1.8.1 and in 1.8.2-pre3.