It's like saying the roads are getting busy because there are more cars on it nowadays. The simple fact that there are more internet users than ever before means that servers have to cope with more users, thus slowing down your connection to the server.
If you are suffering a slow connection however, I would get a utility called SPYBOT...I ran it on my machine and found registry entries that re-routed my Google search engine via another search programme...once I removed them my system was flying. It maybe worth a try.
I think however that ISP's are definately trying to push dial-up users into a corner and thus the services are getting less attention than the broadband users.
Do you have cable access in your area?