without Avast my pc i s more more faster and I'm sorry because I really like Avast.
Sure... I won't expect that an antivirus has zero impact in the performance.
The question point here if it is acceptable, if there are other solutions to this inconvenience.
Protection takes resources. The equation will be always there. Even comparing products, you'll need to compare apples with apples and oranges with oranges.
No the fact is that Avast slow-downs a lot Vista forcing HD frequent loadings/writings. It's not a little (expected by a virus scanner) slow down. With the Standard provider disabled there's a big difference. It's an HD unnecessary overwork. Vista has Superfetch that wroks really fine reducing HD access to minimal. With Standard provider ON every action forces some HD noise, which is not normal.
Just test this: disable the Standard provider (=pause) yourself for a short time and you'll immediately notice the difference in HD loadings. You cannnot deny the difference if you make this simple test.
It looks like Avast routines bypass and don't cooperate with Vista's Superfetch.
As I've already written I tried to disable any option in Standard provider but was still the same. Only way to stop this strange behaviour was to Pause it or uncheck the whole 1st page settings... It's like Nort***n + Kasp***y together on a 486!

Ok, maybe not so slow but the difference is evident however...
PS
How do I disable my email address view in this forum? You can see it? I've set "Hide from public" but I still see the little mail icon aside...