After playing on 2 worlds for a while, I started noticing visual glitches that affect exactly one chunk at a time although any chunk can be affected. This started on both worlds at the same time. Removing some recent additions to the modlist and downgrading recent mod updates, I am unable to remove this affect. (Although disabling FastCraft (which I have been using since the beginning) seems to help more than anything else) They seem to be related to chunk updates because they can be triggered by my machines running or placing/breaking a block. Lowering the number of chunk updates per frame in optifine's settings seems to make the less common. They can be triggered by me moving but not near as often as when placing/breaking a block.
Configs, logs, and options: Here (Google Drive) (Can be downloaded or simply viewed in browser.)