I use python cgi for our intranet application.
When I measure time, the script takes 4s to finish. But after that, it still takes another 11s to show the screen in the browser. 
The screen is build with tables (size: 10 KB, 91 KB uncompressed) and has a large css file (5 KB, 58 KB uncompressed).
I used YSlow and did as much optimization as suggested. Gzipping etc. 
Firebug Net says: 11s for the file.
How do I measure where these last 11 seconds are needed for?
Is it just the size of the HTML, or the table structure?
Anyone more ideas for tweaking?
I think I'd grab a copy of Ethereal and watch the TCP connection between the browser and the script, if I were concerned about whether the server is not getting its job done in an acceptable amount of time.  If you see the TCP socket close before that 11s gap, you know that your issue is entirely on the browser side.  If the TCP close comes well into the 11s gap, then you're going to have to do some debugging on the http server side.
I think that Ethereal has changed it's name to WireShark.  Whatever it is calling itself recently, it's a must-have tool for this sort of work.  I was using it just the other day to find out why I couldn't connect to my virtualized http server.
Measure load time for python cgi script?