I may be wrong but I thought chain zoning is done by entering the zone and instantly sending a location packet to the server that your at the edge of the next zone and then doing a forward step to cross.
So if the momentary shift forward where slowed you might not make the change in location enough distance to make the server believe you hit the zone, leaving you where you actually where when you sent the packet.
But since this is nothing more than my best guess as a complete newb to hacking I could be completely off the mark. But it can't hurt to try can it.
Whats different about being on a mount or not when your talking movement?
Hight and slugish start without "noaccel"
Now my question am I close or clueless?