I would expect a suitable 'build' time for a page (as reported in the footer) to be in the ballpark of just under 1 sec to perhaps 3 secs at the high end, for most shared servers that aren't oversold. Recently, my site experienced builds of >30 secs and I squawked about that- and after about ten emails, they changed something and I got back down to acceptable traffic rates.
As Ich said, many things are going on in the server, so 'your mileage may vary' depending on not just your site's configuration, but any other sites using the same web server and/or SQL database server. If you are logging errors and other visitor details, you're looking at additional traffic. Graphics and scripts from external sites may slow your site also.