ShIMIEs (Shoddy InventoryMoveItemEvents) is a minimal debugging plugin which may help you find the source of Tile-related server lag.
If you have protection plugins such as WorldGuard or LWC, Hoppers can cause an inordinate amount of lag under certain conditions. Looking at timings reports from Spigot, you may find that even a small number of Hoppers can cause considerable amounts of Bukkit events. Specifically, if a hopper is full and attempting to place an item into a chest which is also full (i.e. a backed up item chute), Hoppers will emit up to multiple InventoryMoveItemEvents every tick. While modern protection plugins are typically very efficient, a moderate farm can easily emit hundreds of events every tick, at which point even microsecond-scale execution time can add up to consume the majority of your server's CPU time. If you know where your Hoppers are, it's easy to empty them out. For admins ripping their hair out over seemingly invisible Hopper problems though, it can greatly help to just dump out a list of coordinates.
ShIMIEs has two commands and two permissions: /sh imies (permission: shimies.imies) and /sh tiles (permission: shimies.tiles).
/sh imies <number> records the specified number of InventoryMoveItemEvents and lists their details such as the location and type of the participating inventories (typically Hoppers and Hopper Carts).
/sh tiles <world> simply lists all loaded Tile Entities in the given world to deepen your understanding of your tile-related load profile.
The output of both commands is naturally too large to sensibly convey in a chat message, therefore the contents are uploaded directly to Pastebin, providing the direct link to the command user in chat. Beware that listing the coordinates of all Tiles will reveal the locations of homes and dungeons to all attentive readers.
A Spigot timings report indicating excessive hopper-related load
The admin uses ShIMIEs to locate the offending hoppers.
The dump reveals the locations where IMIEs originate. The items indicate a Zombiepig-Farm
A mod arrests the engineer of the machine (colorized)
Timing shows significantly reduced server load and TPS are back to 20