Thanks for the suggestions.
mclaugh - I tried your ideas with little, if any, improvement. Panther Cache Cleaner looks like a useful piece of software.
klaus - thanks, I thought I was alone! File sizes are typically 20-30mb, I'm going to install VW on a G3 OS9.2.2 today to see if there's any improvement.
RHF - I replaced the hard disk (160gb) and re-installed everything this week - no change. itunes is not open when I use VW.
leonard - I'd also like to hear if there is any improvement in VW11 before investing.
Thanks again - must get back to the drawing board!