I have a bug to report regarding the teleport command:
95% of the time, when a player is teleported to another region they fall into an infinite void. They have to disconnect and reconnect to spawn on the ground (it happens above and below ground).
I think i know what's happening too; its taking a couple of seconds longer for the blocks to be loaded and since its not loaded, the player just falls through where they should be. One way that would fix this is to freeze the player in place for a couple of seconds (configurable) to give the blocks a chance to load/render.
This got worse in recent versions, 2 or 3 versions ago it only happened 50% of the time.
My 7 slot server specs are more than enough and yet this is still an issue:
Intel Xeon E3 1245v2 (3.4Ghz with 4 Cores, 8 Threads)
32 GB Ram
128GB SSD Hard Drive
1Gb Connection
Hosted at a datacenter