[cowfodder]

That sounds great. Mine are much slower than that.

Is tvheadend on the same machine or a elsewhere on the network?

Both. It's running on my Ion htpc connected to the TV, then feeding wirelessly to my desktop a room away.

[patrocks]

Have you seen this thread? http://forum.xbmc.org/showthread.php?tid=135440

It has some info on posts 5 & 6 relevant to channel changing speed.

I've used TVHeadend on same PC with usb Tevii S660 and channel changes are pretty much instant.