David R:
Sorry to take so long to respond. I have been booting my XP every day, recording CPU times for various files, sometimes making changes, then shutting down and rebooting the next day.
I probably confused the issue when I added the Malwarebytes scans. I did that only to see if I might have some malware on the computer. None was found.
The problem with Avast is when I boot my XP computer. As I noted, for the first 4 to 6 minutes or so, the System is idle about 99% of the time while various Windows files and the programs in my startup directory are loaded.
Then AvastUI.exe and AvastUI.svc began to consume CPU usage, and they quickly reached 99%. Avast's CPU usage remained at 99% for about 7 or 8 minutes, then dropped to essentially zero.
You asked if I used the Avast default settings. It has been so long I have no idea how close my settings are to the default. I created a backup file, but I can't read it with any program I have. I would send it to you if you could read it.
When I first contacted you, I did NOT have Avast set to automatically check for updates, nor to do a scan. I did have it set to automatically update for Virus definitions.
My XP computer was custom built years ago by a local shop.
Here is the information on my processor hardware:
IntelCore2 Duo CPU E6550 @2.33GHz 1.98GB of RAM
My software is Windows XP Professional, Version 2002, Service Pack 3.
After you replied, in the general section of the Avast settings, I added 'animate the icon when scanning'. The icon never moves while this problem occurs.
Below are what appear to be the key settings that might have some affect:
1. Program update settings is "Manual update', which I assume overrides the 'Auto-update every xx minutes shown lower on the page. Is that a correct assumption?
2. Enabled rootkit scan on system startup. (in Troubleshooting)
3. Load Avast services only after loading other system services is NOT selected.
4. On the Update screen, my Virus definitions are set to 'Automatic update', and 'Enable streaming updates' is checked.
Even with these changes I was still having problems: sometimes AvastUI.svc would remain at ~ 100% for an hour or so, before I would do a hard reset on my computer. Other times, it would take the 7 minutes or so as noted above.
I then searched this forum, and I found a couple of suggestions from you.
First you said go to 'Add/Delete Programs', right click on Avast, and select 'Repair'. On the XP, there is no 'Repair' option for Avast.
Your other suggestion was to go to the Troubleshooting screen, and check 'Load Avast Services only after loading other system services'. I did that. I first booted that way about 3 weeks ago, and have been running that way every day since. Not clear if made any real improvement. For a few days, AvastUI.exe consumed 100% of the CPU for 3 or 4 minutes, and then System Idle Process returned to 99% of CPU. Then AvastUI.exe was back to consuming 100% for 7-8 minutes. For the last week or so, about 3-4 minutes.
But on Sunday (4/12/2020) AvastUI.exe and AvastSvc.exe only consumed 100% of the CPU for 24 seconds! And at 1 AM (EST) on Saturday (4/25/2020) AvastUI.exe and AvastSvc.exe only consumed 100% of the CPU for 33 seconds! Later on Saturday (4/25/2020, 3:40 PM EST) these two files consumed 100% for about 4 minutes. So the amount of CPU time that the Avast files consume just after boot is now varying quite a bit. But at least it is no longer using 100% for an hour or so.
So what is Avast doing while AvastUI.exe and AvastSvc.exe are consuming almost 100% of my CPU time for 4 to 7 minutes just after booting? Microsoft Security Essentials never did this on my XP, nor does it do it on my Windows 7 Pro.
Harry