chunks loading slowly

chunk loading incorrectly if player gets within proximity of loading chunk

What I expected to happen was...:

the chunk to load normally, and have no lag effect

What actually happened was...:

while approaching the chunk, the world started to lag and the chunk, or multiple chunks did not load, allowing me to see right through into caves and mineshafts.

Steps to Reproduce:
1. open up world

2. go into creative

3. fly right pass chunks