Chunk loading in nether is slow

As you can see in the screenshots, chunk loading is pretty slow in the nether. Once you get this, you can stay still in the area and the screen may go blank, and reload partially. 

Replication:

1. start new world in creative
2. go to the nether
3. start flying around
4. see issue

This is easier to create in lava oceans, than in enclosed area's.

java args:

// -Xmx4G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M