Summary of the problem Periodic 3 second lag spikes Pack Version 1.2.1 What is the bug? Periodically FTB Beyond will "freeze" for 2-3 seconds; it happens during many different activities, and in different places in the world. (Walking around in existing chunks, placing a torch, even standing in place and swiveling around). I have saved & exited right afterwards and checked the "latest.log" file - every time I see something like "16:57:38] [Client thread/INFO]: Default sorting." It happens above ground and down near bedrock - I cant seem to isolate any particular circumstance or actions responsible. I had the same issue in version 1.1.0 and upgrading to 1.2.1 did not help. Mod & Version FTB Beyond, version 1.2.1 Link to log file Is it repeatable? For me = yes. I just start Curse launcher, and open up my FTB Beyond game. Usually within 5-8 minutes I start seeing these lag spikes. Known Fix Nothing I can figure out gets rid of the lag spikes permanently (increasing memory to 6GB, etc). If I play long enough without exiting completely out of the launcher, eventually the lag spikes happen every 10 seconds or so. Also, TaskMan doesn't show anything unusual during the spikes, and background tasks don't hiccup so it seems to just be FTB Beyond.