Choppy lag when walking or running

In version 14w33c, I get a smooth experience when running or walking on a newly created or already existing world. It is great. Now, in version 14w34a and 14w34b, I get a consistent choppy lag when I run or walk – in the same world.

To test I do the following:
1: Create a survival world with the seed "Test Choppy" in version 14w33c.
2. Run or walk towards the ice spike biome. Great smooth experience.
3. Now load the world in 14w34b.
4. Run or walk towards the ice spike biome. I get a consistent jerky/choppy lag spikes.