I've just spent a lot of time with tech support to get an answer. Not sure it's THE answer, but seems to have worked for me. I was asked to remove the following from Mac HD > Library > Preferences > SystemConfiguration:
com.apple.airport.preferences.plist
com.apple.network.identification.plist
NetworkInterfaces.plist
preferences.plist
I restarted the computer & re-chose my own wi-fi network. VOILA. All is working normally. Multiple podcast files, including videos, are downloading at an acceptable speed.
One other thing that may help is to de-select "allow simultaneous downloads" in your itunes Downloads screen to ensure each file goes as quickly as possible. 30-minute podcasts are taking about 30 seconds to download. Perfect.
I still recommend uninstalling & reinstalling before you do any of that if you're able to save/back-up your library of mp3s first. Instructions for that are here:
http://www.ehow.com/how5596597uninstall-reinstall-itunes-mac-osx.html
Message was edited by: grossmusic
Message was edited by: grossmusic