Hi, 1st Post. I’ve been looking at all the posts on the above topic.
I run an EEEPC with MS XP SP2. What I’ve found is that when I set up avast! free anti-virus in the exceptions list in Windows Firewall it performs fine.
OK, CPU goes up to 25K to 30K when it scans an item but then after it’s finished it reverts back to somewhere between 1.5K and 4-5K.
Hope this helps
Well, the scanning take resources and you’ll see a peak.
avast shouldn’t be requiring any firewall exception on Windows XP (inbound protection).
Any other antivirus installed in this computer before avast?
Hi,
I think AVG had been installed but is not now.
I understand that Avast! will peak during scanning as you say.
But, other users in the forums are saying that it won’t go down to less than 25k even when idle.
When I put it into the exceptions list it did go down to the numbers mentioned.
Any more info would be great
It goes down to 1k when idle on XP SP3. 
@ DerekMcC
I take it that you means % and not K for the CPU. The other figures with K in them have nothing to do with CPU use but RAM use
Whilst preparing this post I took a screenshot and that was at 1%, see image, click to expand. That shows the CPU activity at 1% and RAM use with the K after it.
How do you know it is idle, as when my system is idle avast would also be idle, the avastSvc.exe goes down to zero, so you should also be checking for other system activity that would force avast to scan that file usage.
So exactly what do you mean CPU percentage or RAM use ?
If RAM use, windows controls RAM usage and will eventually hand back RAM but it doesn’t do that instantly (as it would have to swap out that RAM date to the pagefile (on your hard disk) should it be needed again. The whole point of RAM is so your computer runs quicker, rather than have to access the hard disk (slowest component in the chain), so RAM is there to be used.
Also if you mean RAM use, what figures are being used as task manager has many different memory figures ?
Hi DavidR,
You’re right. It was mem usage column I meant when I mentioned the 25K
Anyway, yes I’m aware of the RAM eventually being swapped out and given back to the system for other use. And that is what happens on my machine.
I don’t achieve 0% as you do but it goes down to about 1K for me.
What is happening to other users is that it settles down at 25K and no further, as mine did until I added it to the exceptions list in Windows Firewall
The % figure doesn’t relate to RAM use but to CPU percentage use (in the Task Manager, Processes) and I never said my RAM usage ever gets to 0 K, it will ‘never’ get to that. It is a physical impossibility once you run any program that is resident. Even for other programs that aren’t resident when run and open there will be an absolute minimum required to load the program executable into memory.
When a program is actively running its memory will go beyond its minimum requirement, that is what will fluctuate, but it won’t get below the minimum requirement and certainly not to 0 K.
As you can see from my latest image, things fluctuate as far as RAM and CPU activity go, CPU may get down to 0% cpu activity, but RAM will never get to 0 K (System Idle Process isn’t an application, so is an exception), see image2 ordered by those using least RAM (VM Size) and you will see many are using 0% CPU, but aren’t using 0K of RAM.