High server CPU usage even with no players

Server performs poorly with players, and consumes more than an entire CPU core.

Sever consumes >1 CPU core with no players present on the game.

Behavior persists through restarts and exhibits itself immediately upon startup.

Logs and server.properties are attached.

World is available here: https://www.dropbox.com/s/mmgu1nhha7z20yc/take-nine.tar.gz?dl=0