Vlk and kubecj, I presume you've seen other threads relating to near-lockup (on my system, anyway) while avast.setup is doing its thing but before the arrows icon kicks in? Most recently in the "wishlist", I think.
I haven't checked CPU usage, but typically I can't open Process Explorer (or much of anything else) until the icon does appear (at which point setup is apparently no longer active).
I think it was Tech who commented, and it makes sense, that the behavior is totally unexpected from a low-priority service. But it's enough of a nuisance that I'm about ready to throw in the towel and shut off auto-checks and just check manually once or twice a day.
Any ideas?