the way i understand it agility has nothing to do with it (as long as your not
hurt or encumbered that is) - it's the connection speed and most importantly
your computer (including such things as CPU, videocard and RAM) - now for my
experiences

i have 4 accounts and 3 computers running off a cable modem - my computer is a
celeron 450, 196 ram and voodoo3 - my roommate has a p2 300, 64 ram and a rage
pro card - the third computer is a p2 200, 128ram and a pos video card

i'm a level 29 half elf bard - he's a level 31 half elf ranger - while going
through the karanas i have to follow him or after a few mins he'll be out of
range of my song and i'll leave him in the dust - now we decided to play around
with it a little bit and when i log onto my account on his computer i never lose
him but when i'm on mine i have to watch him using 3rd person per and i stop and
wait when i see my song pulse not hit him - now when i log on with the 3rd
computer i always have to wait and make sure i don't leave them behind so i
usually just play on that computer and have my computer's char follow me instead

now i know it's not lag as we're all running on the same network and since we
switch computers to test a few things out my conclusion is that the only things
that make people go faster is a better computer/connection - now i know this
might not be enough evidence for everyone but it was enough to convience both me
and my roommate but i dunno - maybe we're just weird