Somewhat strange computer speed issues

[Aram]

I've been experiencing significant computer slowdowns when using uTorrent, with a somewhat strange pattern, but first here are my specs:

Pentium IV 1.6 GHz, 384 MB RAM, Win 2000 SP 4 (with all available patches)

Two 120 GB 7200rpm hard drives in a RAID 0 array

Not using a firewall, using Kaspersky Anti-Virus

Firstly, I'd like to point out that this issue occurs with the AV unloaded as well, so don't blame the antivirus straight away. Whenever I'm downloading files in uTorrent, I experience very significant slowdowns of my system, to the extent that there's a lag in the mouse cursor in explorer. The slowdowns are so great, that they even make Winamp sound choppy (even with a large buffer), and nothing, not even Civilization IV, which takes up all my system resources and then some, ever managed to bring down Winamp playback before. During this slowdown, not a lot of memory is used (around 300MB), physical memory still being available, and CPU usage by uTorrent is in the 40-80% range, with occasional spikes to 100%. There are also no other processes exceeding 5-10% CPU usage at that time. The computer speed returns to normal as soon as I quit uTorrent or pause all the downloads.

Now the thing that's strange about the slowdown, is that the computer gets slower the longer uTorrent is running. When I first open uTorrent after a restart, other programs function smoothly, but in an hour or so the slowdowns become noticeable, and after 15 hours the computer is almost unuseable (restarting uTorrent does not "reset" the slowdown, only a computer restart does). This occurs even if I restart, open up uTorrent and go to sleep, after which I find the computer increadibly slow in the morning, so it is definitely uTorrent that is causing this (no such slowdown occurs if I'm not running uTorrent, even if I keep my computer on for weeks). Setting the uTorrent process priority to low has almost no effect, I'm assuming it's mostly the hard drive accesses that are causing this. My RAID controller is also not to blame, as I only set up the two hard drives recently, before that I was using a single IDE drive (in UDMA mode) with the same problem.

Is there any way to alleviate this problem, besides having to restart the computer evey couple of hours?

[Firon]

Run Sysinternals Process Explorer and see if the DPCs are using a lot of CPU.

Also, have you tried -uninstalling- the AV to see if it still happens? Disabling tends to not work.

[silenthill]

i have the same problem. after 2-3 hours CPU usage by uTorrent is in the 80-100% . i don't use antivirus or firewall

[Firon]

silenthill: make your drives haven't been reset to PIO mode

[Aram]

I checked with process explorer, and yes, the DPC calls are taking up a lot of CPU, in fact, they use all of the CPU that isn't used by uTorrent. Am I to understand that this is due to faulty device drivers?

As for the antivirus, I'm sure it's not to blame, since when I unload it, I make sure that there are no AV processes running whatsoever. In addition, when the AV slowed down the system in the past (like when extracting an archive with lots of files), it was pretty clear that it was causing the slowdown by its CPU usage.

[Firon]

Yes, it's most likely due to faulty device drivers/hardware. Also, make sure your drive hasn't been reset to PIO mode (check the ATA controller).

But for kicks, just try uninstalling the AV to see if it goes away.

[Aram]

I uninstalled the AV yesterday, and haven't had any of the speed problems since. I guess I was wrong. Thanks for the advice. I was wondering though, how did you immediately know that the DPC calls have something to do with it?

[Firon]

Usually when people have strange 100% CPU issues like this, there's DPCs using a lot of CPU (which do NOT show up in the task manager). And if there are, it means there's either faulty drivers/hardware, or some software causing a severe conflict. This isn't the first time it's happened to people here, methinks.