I am having some issues with download speeds on my site via http, i am averaging around 70kbps downloading a file that is around 70mb.

But if i connect to my server via FTP and download the same file on the same computer / connection i am averaging about 300+kbps.

I know my server has alot of connections at any one time, probably around 400 connections.

My server has a 1gbps connection to the internet so there is plenty of bandwidth available, as proven with the FTP.

I have no throttling of any kind enabled in IIS.

If interested there is a test file here you can download to check the speed: http://filesd.house-mixes.com/test.zip

I am based in the UK and the server is in Washington, USA if that makes any difference.



Found out the reason for the slow downloads in case others have the same problem.

I was running a tool called IISTracer on my server, apparently there is a known issue which reduces file download speeds to around 80kbps.

As soon as i disabled this my download speeds shot up to 330kbps!


While FTP is and should be faster, not that much.

Have you tried any packet sniffer , port scanning / tests?

  • No and i'm not sure what I would look for when doing so, i'm downloading wireshark now...what do i need to do / look out for? – Paul Hinett Mar 19 '10 at 19:44
  • Truthfully, I use a hardware based packet sniffer, I dont use software ones, but, the software relies on your computer. Hopfully soneone with software based packet sniffers will reply, but, basically you should be able to run a test with the sniffer while little to no traffic is happening, then test again during normal browsing the web, then test again trying to download this file. This will give you an idea as to if it is on your end or not. It's a starting place. ;) – Tom Mar 19 '10 at 20:16
  • using a scanner is a good way to alert any sysadmins that your up to something... – djangofan Mar 19 '10 at 23:57

Quite possible that your isp is throttling http traffic, or your http trafic is taking a different route to other traffic. If you going through a transparent layer 7 http proxy/cache it may be overloaded.

Try using some online tools to see if your being proxied.

  • I have another dedicated server hosted by Fasthosts here in the UK, i tried the same tests on that machine and received the same results. I think this rules out anything to do with my ISP? – Paul Hinett Mar 19 '10 at 22:20
  • When i said ISP, I'm those providing your internet access, not the isp hosting your server. Sounds like your isp rate limiting you. – The Unix Janitor Mar 20 '10 at 20:08

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