Been playing on a server for about a week now and we started to notice that when entering certain chunks the servers tps dropped to 0.7. And it's only when we enter the chunk, if we stand on a block that is directly outside of the chunk and build inside the chunk everything is fine. (we think this has to do with a crash the server had but we are unsure as we reverted to a backup when it happened). The console says nothing not even running behind or anything and it's only the overworlds tps that drops so anyone in another dimension is fine. Any idea of whats causing it and/or how to fix it?

--EDIT updating the pack to v5.2 did not solve the problem and we still have some chunks we can't enter if we want to play

Found the issue. somehow 20k items had dropped in a chunk and was not loaded until you entered the chunk. We installed tickprofiler to find out what was causing it.