[MC-45458] Framerate drop/lag in 1.8 for some hardware setups

Possible Fixes to reduce the lag:

Turn down the graphical settings or upgrade your Hardware.
Also, for some users, Java 8 fixes the issue: http://www.oracle.com/technetwork/java/javase/downloads/jre8-downloads-2133155.html
Some users have noted improvements when using 64 bit java instead of 32 (when applicable).
You can also try to update any graphic card drivers for your system.
Things have changed, a performance boost is not guaranteed with 1.8.

Compared to 1.7, the framerate is (much) lower in 1.8, including lags while generating the world.