I started a new world to test how 1.8 plays for me. After a few game days of gathering local resources, I decided to go explore past the immediate area. After going over a hill, I found a section where the world kept flashing between possible biome and render options - flat, hilly, taiga, forest, and even lava. I tried walking forward into said area to see if the graphics would stabilize, but they did not. The following screenshots happened in rapid succession.

Also, I don't know where to report this, but the new fps improving rendering system does not work for me. I struggle to hit even 5 fps. Occasionally, I will get a couple seconds of 20+ fps, but most of the time it's a struggle to do anything. May or may not be related to the world rendering issue, just thought I'd mention it in case it is.