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On my machine (win-xp SP3) at work the Internet seem slow, every page takes > 20 seconds to load. So I tried to diagnose the problem. Here is what I did :

  • Check the internet connection speed
    • I went to The test took a long time to start, but when it started went pretty fast. 12ms ping, 9.36 Mb/s download and 0.73 Mb/s upload. I did the same test on another computer on the network and got the same result, but the page loaded faster and the test started right away.
  • I tried this in differents browsers

  • I check the ping time to some server on the internet.

    • ping gives me times of less than 30ms ( still takes more than 20 seconds to load on this computer while it takes less than 4 seconds for others machines on the network)
  • I thought it could be slow DNS resolving, but the addresses seems to be instantly resolved when I do pings

  • I disabled the AV, didn't change anything.

What should I test next? It seems I've eliminated every possible source of the problem I know.

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up vote 3 down vote accepted

Try Fiddler2 Link Here

It can find exactly what code is taking the time and possibly point you to the source

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Hi DaveM, Fiddler2 helped me find the problem. The AV that was installed some weeks ago acted as a proxy for all the browsers and was taking 10-15 seconds to release the queries (when I saw them in Fiddler). Also Fiddler was showing that all queries were comming from the AV. – Mathieu Pagé Dec 2 '09 at 19:25
Glad it helped. Has helped me a number of times. – Dave M Dec 2 '09 at 19:45

It's very odd that your d/l speed is so much slower than your upload speed. Something doesn't seem right. Perhaps your machine has some malware running downloads on it? Does the network activity panel of process manager show any activity when your machine should be idle on the network?

If your numbers were a typo (that is, your d/l speed is 9.36 Mb/s), try running Firefox with Adblock Plus and Noscript to rule out the possibility that ad and script servers are not the bottleneck of the pages you are viewing.

Try running a long-term ping to a large internet site:

ping -n 100

If you have any packet loss, then there's a problem, likely with your local network (a machine/device flooding the wire, etc.) or your ISP's network.

Also, your specific IP could be getting DoS'ed or flooded. If you have a dynamic IP address, I'd try powering off all of your networking equipment and PC for a minute or two and seeing if things are improved after a restart.

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Microsoft does not respond to Pings or TraceRoutes anymore. – justSteve Feb 18 '12 at 21:11

Fiddler is good, but a more detailed analysis can be made using YSlow.

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