Weird Behavior of the end portal block:
Overworld: really bad wiggle and texture
Nether: not AS bad
End: completely normal
Testing was done in a DEFAULT world generated with the 16w39c snapshot
For a more detailed look, watch: https://youtu.be/69VPpplOZ7k
Environment
Windows 10 Anniversary Update
Java 1.8.0_101
PC: - i7 5820k @ 4Ghz - GTX980 (driver: 372.90) - 16GB RAM
Cannot reproduce. Please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report (minecraft/crash-reports/crash-<DATE>-client.txt) here.