I have no frame of reference in terms of what\'s considered \"fast\"; I\'d always wondered this but have never found a straight answer...
You can search "slashdot effect analysis" for graphs of what you would see if some aspect of the site suddenly became popular in the news, e.g. this graph on wiki.
Web-applications that survive tend to be the ones which can generate static pages instead of putting every request through a processing language.
There was an excellent video (I think it might have been on ted.com? I think it might have been by flickr web team? Does someone know the link?) with ideas on how to scale websites beyond the single server, e.g. how to allocate connections amongst the mix of read-only and read-write servers to get best effect for various types of users.