Thanks for the replies, guys. I gave up earlier. The Boat bad comment was a freudian typo but I couldn't get to the edit page to fix it!
Sorry JF. Now the traffic is low, I'm back to normal speed.
Alex, I'll do a trace next time it slows up....teatime tomorrow. I've checked the line speed and it reports ok.
Edit: I've just done a trace while speed is good. It'll be interesting to compare the timings at various points when it's slow.
Is it possible to dump the contents of a DOS screen to the printer or copy/paste it?