How To Diagnose a Suddenly Slow Windows Computer?

Ensign Taco writes "I'm sure nearly every one of us has had it happen. All of a sudden your Windows PC slows to a crawl for no apparent reason. Yeah, we all like Linux because it doesn't do annoying things like this, but the Windows desktop still reigns supreme in most managed LAN work environments. I'm running XP with 4G of RAM and a decent CPU, and everything was fine, until one day — it wasn't. I've run spybot, antivirus, and looked at proc explorer — no luck. There is no one offending, obvious process. It seems every process decides to spike at once at random intervals. So I'm wondering if there's a few wizards out there that know what to look at. Could this be a very clever virus that doesn't run as a process? Or could this just be some random application error that's causing bad behavior? I've encountered this a few times with Windows PCs, but the solution has always been to just add more hardware. Has anyone ever successfully diagnosed this kind of issue?" And whether such a problem is related to malware or not, what steps would you take next?

Comments

Try this

[Anonymous Coward]

Unplug the network cable in the back and see if the problem persists. The network is a common cause of this problem.

Still...

[Moraelin]

Actually, while I do somehow sped more time at home on my Windows gaming box than under Linux (so this isn't a blanket Windows bashing,) my superficial and uninformed impression was that, all else being equal, any Windows box I've seen seems harder hit by IO than any Linux/Unix box I've ever seen.

Yes, you can get a Linux box to crawl too, if the hard drive is stuffed and it can't swap for example. Or if the chipset isn't supported well by the drivers. (Rarer these days, but certainly possible.) Or whatever.

But Windows... seems a bit special. I mean try to copy a directory between two hard drives, or better yet from a DVD to HDD, and Windows seems to me basically stuffed. Even notepad can get about as responsive as a narcoleptic snail. And you can just about forget about, say, playing a game while that happens.

And that's before you even add such brakes as an anti-virus.

I've seen that behaviour in any Windows, from 3.0 to Vista, including a detour through NT 4.0. In fact in Vista let's just say there's a reason why so many people were pissed off at the indexer kicking in all the time.

My subjective impression is that I've yet to see Linux get anywhere near that unresponsive, in a similar scenario. Again, assuming that you don't have a nearly dead HDD and the chipset is supported in DMA mode.

But heck, even in PIO mode, I've used Linux in PIO mode and I've used, say, NT in PIO mode. (Thanks to a retarded IT department which installed the wrong IDE drivers.) Linux did obviously have poor file IO performance, but NT just freaking _froze_ for a second or two, for example, when minimizing or maximizing a window. (Presumably due to aggressive memory management which swapped more of a process out when minimized.)

Now admittedly I haven't actually programmed an OS at any point, so I'm probably talking out the arse, but I see no reason why that should happen at all. Any common source of IOWait has an interrupt. Even in PIO mode you don't have to poll until it's done. And DMA, now that was invented for the precise reason and purpose of transferring some data while the CPU services another process. It's why it's there. So there's no freaking reason for the whole OS to just twiddle its thumbs and wait. Even if one process is waiting for _paging_, you can still yield to another process while waiting for the HDD.