So, it was brought to my attention that the way that I am teleporting the player using commands seems to cause some rather bad happenings on the server. When I first tried it, after they found the issue, I tried to teleport from the overworld to the end. When I did it had me suspended in what looked like the end, but nothing was loaded, no blocks could be seen, I couldn't move, nothing. Eventually my client disconnected, and then when I tried to log back in the server crashed saying that the server took a 60 seconds for a single tick. 

 

The way that I am attempting to teleport the player is just like how they do it in minecrafts code 

(pulled from the end portal block code)
 

entityIn.changeDimension(worldIn.dimension.getType() == DimensionType.THE_END ? DimensionType.OVERWORLD : DimensionType.THE_END);

 

What I am doing is this:
 

	public static void teleport(ServerPlayerEntity player, Location loc) {
		PlayerData data = Main.database.get(player.getUniqueID());
		data.prevLoc = getPlayerLocation(player);
		BlockPos pos = loc.getBlockPos();
		if(!player.dimension.equals(loc.getDim())) {
			if(Main.isDev()) {
				player.changeDimension(loc.getDim());
			}else {
				TextUtils.err(player.getCommandSource(), "The ability to teleport between dimensions has been disabled until it can be fixed.");
				return;
			}
		}
		player.setPositionAndUpdate((double)pos.getX() + 0.5D, (double)pos.getY(), (double)pos.getZ() + 0.5D);
	}

I feel like something I am doing must be the issue, it is normally the reason, but I was fairly certain that this would work.

Teleporting players is a messy business. ServerPlayerEntity#changeDimension() has all kinds of hardcoded stuff that assumes it was called from a vanilla portal, and therefore isn't really suited for general purpose use. You can try ServerPlayerEntity#teleport() instead. Be warned though, ServerPlayerEntity#teleport() will not work from Block#onEntityCollision(). If your are using it only in a command you should be fine.