Board Thread:Bug Reports/@comment-27539589-20160321234429/@comment-26172435-20160322194023

Okay, this helps. A number of things are non-default and likely to cause instabilities: Additionally:
 * Your java version is outdated. Make sure you install java 1.8.0_25.
 * You're using Optifine. Don't. Fastcraft gives you the performance smoothness you need and Optifine just bugs with this mod.
 * You're maximum allocated memory is set to just 1 GB. See 'JVM flag -Xmx1024m'. Set that value to 'Xmx2G' instead.
 * Your Forge version seems okay. If all of the above adjustments don't help, revert to version 10.13.2.1231.
 * You have NEI installed. Add the add-on for this mod, provided to you by The Ranger Malvegil. See this thread for the latest version.

Good luck!

Note that there are various threads in this forum that hold an explanation on how to change JVM flags, Forge, etcetera. This may help as well: