I'm running Vista x64 sp1. I've had IE 7 and then IE 8 (b2) installed. I tried uploading via ftp from a)Windows Explorer, b)Visual Studio ftp, c)FireZilla, d)SmartFTP. Small files uploaded perfectly but even 150KB files kept timing out and retrying. Active/passive didn't help. Nothing helped. I tried for 28 hours to upload a 340KB file. It was infuriating. I tried from another ISP's connection. I tried from XP. Nothing worked. God knows why. I contacted tech support, they said it was a problem on my ISP and that my connection was poor. While I agree a 100kbps upload isn't good at all, I do expect to upload 100KB in a few minutes and not failing for hours. I can't be too sure about their response as people using my ISP DO upload via ftp. I sent my files to a friend in the US and he graciously uploaded for me. He mentioned it was slow. And then I needed changes on my site. Enter frustration.
Well...just now I found a brilliant solution that's just plain mind boggling. I learned of FireFTP, an ftp plugin for FireFox. Now, (this may surprise a lot of folks), I don't like FireFox much. On my dev machine, it's painfully slow loading pages from the VS dev server compared to IE7 / IE8 / Chrome. But this is one thing I'll always be using for ftp from now on. You see, FireFTP is slick, fast and it uploaded my 350KB file in 25 seconds flat(!) - something the bigger players failed to do.
I'm guessing this is coz of some OS configuration or firewall or whatever. I tried turing off vista auto tuning. Nothing helped. I faced the same problem from XP though. I wonder if it's my good buddy Kaspersky that's causing me the pain. I did try turning off the firewall, but that didn't help either.
Anyhow, I'm glad I found fireftp. I noticed some people on the forums were complaining about slow ftp too. I hope fireftp can help them too.
EDIT: As Josh points out...I really should have posted this link here:
FireFTP: The BEST and SIMPLEST FTP software I've EVER used - and one that just "works".
There you go :D