Any time a player teleports (by any means such as: Raw commands [/tp, /tpa], Journeymap, Waystones), the server will hang momentarily, keep running and then all players will time out. It happens every time with unloaded chunks (client will receive chunk data, then time out), and roughly half the time into loaded chunks (similar story, chunk data --> time out).

latest.log

Leaving this comment here for anyone else who comes across the issue, it appears that disabling sync-chunk-write in the server properties solves this issue.