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I don't use torrents often so this may be just something simple I overlooked. When using uTorrent (haven't tried any other clients for now), although download+upload speed are not 10% of my connection, the browsing speed goes to hell (extremelly slow).

Anyone knows what could be the most probably cause ?

Platform: XP SP2

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up vote 3 down vote accepted

What OS are you on? If it's XP, try this TCPIP.sys patch.

The problem is, XP (and pre-SP2 Vista) only allowed 10 "half open" TCP/IP connections - a half open connection is one trying to connect, and an open one is one that's connected. Normally this isn't an issue, but bittorrent makes a LOT of connections - seriously slowing down attempts to make any more.

Edit by ldigas: patch for Windows XP SP2 (from RC2 upwards) or Windows 2003 Server SP1 beta

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Yes, more than the bandwidth, there is a problem of number of simultaneous connections. – Gnoupi Jan 16 '10 at 22:37
Hmm, interesting. I see this is for xp sp3. Is there some solution for sp2 (which I'm currently running). I wouldn't like to go to sp3 for now. – Rook Jan 16 '10 at 22:40
There should be, somewhere, but I'm afraid it's been far too long for me to recall where :( – Phoshi Jan 16 '10 at 22:57
Found it. Thanks Phoshi ! Hope you don't mind me messing with your answer. – Rook Jan 16 '10 at 23:28
Certainly not! Thanks for adding the right stuff :) – Phoshi Jan 16 '10 at 23:40

Look into a traffic shaping solution. I have been using cfosspeed for a few years, on XP and now Windows 7 x64.

That said, I still find reducing my utorrent number of connections to 50 (active seeded torrents can still be 1000) helps a lot - with or without traffic shaping.

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thanks. i'll check it out! – Rook Jan 17 '10 at 0:20

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