OK, I understand what you mean now. I get the same.

I have my alts on a seperate screen and when I look at that, they're following me at close range. But when I look on my main screen they appear to be lagging well behind. I suspect it's an artifact of WoW; something to do with client side prediction and latency. The alts know they're on follow so if they're told that the main has moved, they know that they need to move. The main doesn't know he's being followed so displays the alts in the position he was last told they were in by the server.

I suspect I'm not making much sense here so I'll try a sequence of events.

Main: Moves.

A packet gets sent to the server to tell it where it moved to. <- Latency

The server sends a packet to everyone else in the vacinity (including the alt) to let them know. <-Latency

Alt: Now knows where the main is so knows where he needs to move and does so instantly.

As the alt has now moved, it sends a packet to the server to tell it where it is. <- Latency

The server sends a packet to everyone else in the vacinity (including the main) to let them know. <-Latency

So from the alt's perspective, there's no latency and they follow snugly behind the main.

From the main's perspective, the alt appears to lag well behind.