Hello, all, I am somewhat moderately knowlgedable about computer; I had a problem with my Apple iTunes running slower than it had before on my machine. I don't think I've done anything different but recently it started to get slow, as in .1 megabytes per second download, for even single files. It frustrated me when I downloaded movies that would take maybe part of a day to download, specially HD movies. Now I went surfing around and didn't find too much helpful information, but something did help me. I ran the diagnostics for iTunes network connectivity tests, which I looked in the information at the end that I could copy to my clipboard and noticed that iTunes said it was NOT enabled through Windows Firewall. I looked in Windows Firewall and saw that is showed it was enabled. So I decided to add it again, which I went and added it in again. Then I went to my router and added the TCP port 5223 to port forwarding, and now I get .4MB-.7MB per second instead. What I think happened is that after updated it, or/also since I am on Windows 7 64 operating system I went and added the iTunes 64 version. So maybe an update disconnected the enablement from Windows Firewall, or it had an issue with it being the 64 version or both. Now I know work ones can be cheaper with computers so I know my work likes old computers so it uses the regular Windows 7 and not 64 bit. So maybe that is why it works better on some and not others.
So the process, from iTunes' "Help" tab click it and then click "Run Diagnostics..." Have only "Network connectivity tests" selected hit the "Next" button then the "Next" button again and the "Next" button again. Under "Firewall Information" look at and see what it says, it might say "Windows Firewall is on" "iTunes is enabled in Windows Firewall" if it says something like "Windows Firewall is NOT enabled in Windows Firewall" then go to you "Start Button" click it and click "Control Panel" then click "Windows Firewall" you might want large icons as the view by option to find it easier, then click "Allow a program or feature through Windows Firewall" and make sure to scroll down and see iTunes, and I made sure that I had clicked both options of "public" and "Home/Work (Private)" for iTunes as in checked. Then I clicked the button "Allow another program..." scrolled down to iTunes, and clicked it and then clicked the "Add" button. And made sure both "Public" and "Home/Work (Private)" were selected, as in checked.
And I instantly saw my speeds increase, then I went to my router's address and went to port forwarding and added the program iTunes to my computer's address and put 5223 for the TCP. I won't type all the steps for port forwarding because I think that all routers are different. So maybe look around and see how to forward ports on your router.
Hopefully that is enough information to get even the less tech savvy through to be able to get faster speeds. I would say I am more intermediate to advance level tech savvy than expert. But at my work sometimes I help the tech dude when he is overwhelmed. I am used to typing up long winded explanations for those with even barely the ability to use a mouse so sorry to those with more knowledge that end up reading this whole thing.
So remember this is what I did to "fix" my speed issues. Much happier now. I hope this helps you if you have slow speeds as well.
-DeeHunt