wireless speedup/slowdown

[Filippos]

> Would that mean badly configured DNS servers on someone else's machine, like
> my ISP's (who is the local telco)? Or on my own system (which is not running
> one)?

That's right, it's the badly configured DNS servers outside that slow 
IPv6 down. Actually the last link that I provided is the solution to
turn IPv6 off. That way you can see if it was a DNS problem after all.