I’ve only recently started playing MeseCraft and so far I’m really enjoying it. However, in my single-player game after mining down to a depth of about -130 my FPS suddenly dropped from 60 to about 5-10. Going back up even just 5 blocks brings the performance back to normal. There’s nothing really interesting in that particular location – just some tin ore, which couldn’t be the culprit since gathering it all up didn’t fix the problem.
During the lag a single CPU core is used up at 100%, and the longer I stay at that location, the worse the lag gets – so maybe something is being generated? I haven’t yet tried to get to that depth at different location to see if this occurs throughout the entire map.