https://www.google.fr/search?q=exception+in+server+tick+loop&oq=exception+in+server+tick+loop&aqs=chrome.0.57j60l2j62l2.234&sourceid=chrome&ie=UTF-8
1er lien :
http://terrafirmacraft.com/f/topic/2652-solved-annoying-crash-exception-in-server-tick-loop/
[SOLVED] OLOL PROBLEME RESOLU
POSSIBLE FIXES
1. Could be your version of Optifine
2. Increase the numbers of ''maximum chunks per ticket" and "maximum ticket count" in forgeChunkLoading.cfg
3. Update your LWJGL
4. In Optifine, change the chunk updates option to 5
5. Could be a problem with MultiMC