Ah interesting. Maybe it was a case of me being naive when I was learning perl and writing my first scripts :) I always thought that the sleep command was only to be used in SSH (as it had no effect in the web-browser). Thanks for clarifying - although that now means I've lost a bet :D
I have to admit - I've never had a reason to use sleep to "slow down" a script running in a web-browser - its only really when doing scripts that would need to leave a little gap to help the server cope with larger processes via cron etc