Low TPS from entities/hoppers?

I'm getting huge performance hits from, what looks to me, mostly hoppers or entities. This seems to happen at random times, and regardless of how many players are online (could be 3, could be 20) and won't go fully back up to the usual 19.5+ tps until the server is restarted. 

https://timings.spigotmc.org/?url=cunarejule

Is there anything weird going on here? There's one area of the map I know of that has a rather large amount of hoppers, but that area being loaded doesn't seem to coincide with this issue coming up.