Actually, I did notice something odd that might be pertinent after all.

It's the only noticable performance and response problem I've had
in a long time.

A couple of weeks ago, I got a new disk for my laptop - replacing
the (by now very noisy) 10G IBM travelstar with a 40G, 4200rpm
travelstar.

I also got a little usb2 external disk case, to put the old disk
in.  I used that to facilitate the copying process, first putting
the new disk in there and writing out new filesystems from the data
on the old disk, before swapping them.

The laptop only has usb1 ports, so it was of course a slow process.

But the whole system did get very, very slow while writing out the
data. A little like you describe - switching desktops and moving
the mouse was laggy, and drawing held up. I saw this in X while
dd'ing the NTFS partition acrosss - I was of course in single user
when dump|restore'ing the NetBSD filesystems, so wouldn't have seen
it then.

At the time, I put it down to something in the usb code -
but perhaps it was somewhere else and the really slow disk
highlighted the problems you're seeing?

It shows up as sd at umass, btw, so it's not wd specific in this
case.

--
Dan.