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I am on Windows 7. My computer has been pretty slow on a regular basis. RAM doesn't seem to be the issue, but my CPU usage is through the roof, which is causing my fan to always be running.

I figured out that the high CPU usage comes from svchost.exe and ezSharedSvcHost.exe. They are using around 20 and 10 percent of the CPU respectively (which is a lot on a quad core like my computer).

I have Norton installed and run scans frequently, but could it be that I have a virus running through one of these host processes? I'm not sure what I would have downloaded that could give me this virus.

My understanding of Windows host processes is that they load DLL services which can't be executed on their own (as they are DLLs) to allow them to run or allow other processes to use the loaded binaries. If I have a virus, it will probably appear as a mysterious DLL not belonging to Windows, correct? If I don't have a virus, then it's just Windows doing its best to overheat my CPU, probably downloading updates, correct again?

Is there any way I can figure out how to get rid of a virus in the unlikely event that I do have one Norton hasn't caught, and is there any way I can reign in Windows' massive CPU usage in the more likely event that the operating system is working very hard to cripple my system?

Still, the slowness perplexes me. Even with the equivalent of one core bogged down with host processes, my computer still has three cores' worth of CPU to do stuff I want it to do. Hard faults (paging to and from hard drive), which makes the speed of my drive the bottleneck.

With RAM to spare when this happens, why would there be so many hard faults? Could it be I have mis-diagnosed the problem? It's very hard to look at what system resources are being used the most during one of these slow episodes because I can't usually get the task manager open, so I usually catch the tail end of the problem.

share|improve this question
I would check to make sure the CPU's not overheating. That can cause excessive CPU consumption by ordinary tasks because the CPU throttles. – David Schwartz Nov 7 '12 at 21:01
I'll do that and check back in later when I have an answer. You may be right... – Big Endian Nov 7 '12 at 23:45

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