I have Windows 7 Ultimate with Avast! Internet Security on a fairly powerful 8 core workstation. I've used it for years, and it's very stable and efficient.
However, I've noticed that my system gets slower to respond after it has been running for some days (I leave my system running and logged-in 24/7).
At this moment my system has been running for 10 days 13 hours, and when I start an Explorer window, it is taking about 4 seconds to show the window on the screen. This delay/sluggishness is occurring with opening any application - the desktop has simply become less responsive. Normally, after a fresh reboot, the time betwen starting Explorer from a desktop icon and seeing the window open is not noticeable (i.e., it's instantaneous or at worst a small fraction of a second). The problem is NOT resolved simply by logging-off and logging back on. The problem IS resolved by a reboot.
I set out to discover what was slowing things down using ProcMon, and I noticed that LoadImage commands were each taking something like 0.1 second to complete, which adds up to several seconds overall.
Thinking about what could be affecting something as simple as loading a DLL, my thoughts turned to the Avast product, and sure enough, when I temporarily disable the "shields" the time to open an Explorer or other application window is back to being instantaneous.
A bit of further trial and error showed that just disabling the Behavior Shield averts the delay, and even further that the [ ] Monitor the system for unauthorized modifications setting is specifically responsible.
In summary:
After running Windows 7 for days (e.g., longer than a week), the Avast Behavior Shield function "Monitor the system for unauthorized modifications" setting causes big slowdowns in normal Windows desktop operations, such as starting Explorer windows.
System performance returns to normal (virtually instantaneous) after a reboot. However, I do not need nor want to reboot the system.
I am not sure whether the slowdown is progressive over time or happens all at once, but it does seem dependent on how long the system has been running since the last bootup.
Can you please advise what I can do to avert this problem without a reboot?
For now I'm working around it by disabling the specific shield function that is tied to the slowdown using the Expert configuration capabilities, but I'd like to turn that back on.
Please let me know if there is more information I could provide for you to help narrow this down.
Thank you.
-Noel