Thanks alot, maybe i use the support-system sometimes, but now i have the problem solved by myself by using process explorer always on.
I use FreeCommander, and always if i used with FreeCommander Folders with thousands of files, avast needed later so much CPU.
The solution is simple: Disable the Cache like in the screenshot. maybe is the problem only at my computer, because i have disalbled scanning files in the real time file system shield. Therefore maybe avast never have updated my working folders, and have always the same problem with it. It make always the first time procedure... because never was a file scanned.