I the last weeks I used Fiddler  to see what is sent over the lines on initial start of a web site and during the web application is running. You can simply mark more than on request line. On the right side you will then see in the Performance Statistics how many bytes are received from the client.
When you have a look at Live.com  you will have this result:
If you are using a 28,8 modem (3.600 bytes/sec) you will need more than 3 minutes to show this page. I'm currently searching for a tool that will restrict the bandwidth use when accessing a web site (maybe as HTTP proxy) to see current web sites running on slow connections. Yes, you can use ZIP compressing for all the files, and this will speed up the request, of course!