thanks theducks, I have taken off the write caching to be safe, still have the time at 25s so it must have just been coincidence that I tried the change and thought it was the reason for the improvement
thanks ilovejedd - from the info you gave me I found this
http://manual.calibre-ebook.com/portable.html - will try to make sense of it and work out how to get CALIBRE_OVERRIDE_DATABASE_PATH working - looks to be a way thru and I am not fussed with multiple library support