Odd FPS in 1.7.0.3 Beta

Description: Starting in the 1.7.0.3 beta update, Minecraft took an odd FPS drop (as reported by NVIDIA GeForce Overlay).
In 1.7.0.2, in creative infinite worlds with 72 chunk render distance, the game would run at about 60 - 75 FPS when the world was loading and rendering buffers were being built and continued to run at that FPS when it was finished (no more chunks loading and being rendered).
In 1.7.0.3 in creative infinite worlds with 72 chunk render distance, the game's FPS varies. When you start a new world, it starts out at around 60 to 75 FPS as it used to but quickly starts to go down once the world starts to get bigger. Having a large mountain in front of you seems to raise the FPS back to 75, likely due to culling. Looking straight down also increases FPS but looking at the horizon gives about 25 - 40 FPS.

• Steps to reproduce (at least on my machine):*
  Set all video settings to minimum (few seem to make a difference)
  Set render distance to 72 chunks.
  Create an infinite creative world
  Fly up to see as much of the world as possible
  Wait for world to finish building, look around to load chunks behind you.
  Note the FPS while looking in different directions.
  Set all video settings to the max
  Notice how little difference this makes to the FPS

My machine should be easily able to run Minecraft at 60 FPS with max settings.