I am new, but I will try to provide clear and useful information.

Since 1.12.2 I experienced major TPS lag. Narrowed the issue down to WorldGuard, but the developer believes it is a bug in Spigot.

Seems like there was an update to hoppers and this is causing some CPU drag.

1) CPU profile generated by WorldGuard [http://paste.enginehub.org/HNZpQO.profile
]

Note that Hoppers are using up roughly 80%. 

2) Contact with developer of world guard (lower comments)
 http://dev.enginehub.org/youtrack/oauth?state=%2Fyoutrack%2Fissue%2FWORLDGUARD-3870

3) Additional images for context* Note: TPS was 10 on server. Screenshot from offline/independant test.
https://www.spigotmc.org/attachments/2017-10-02_17-30-50-png.285364/

4) Temporary workaround by removing WorldGuard.