sandbox initiated file system shield scanning

I’ve noticed this two months ago when I started using AIS, but because of sandbox related BSODs i didn’t use it so I had no problems. then yesterday this was reported http://forum.avast.com/index.php?topic=71883.0
Confirmed it on another XP system so the problem is:
If you set a browser to always run sandboxed (didn’t test with another type of application) FSS scans microsoft type of files (.doc, .xls, .pub). office 2007 files don’t get scanned. then checked windows/installer folder. it also scans
.msi .msp .mst files but not all of them (on my system 240/300; it appears that some are checked in avast definitions folder so do not get scanned). so, when you open a folder with many microsoft files there is a big slowdown in navigating (e.g. my documents). these files get in transient cache, and later when you open the same folder, there is minor slowdown (but noticeable). attached procmon picture
edit:scanning happens “on view” (i.e. when file is visible) ;D

Please read:
How to invoke memory dump creation?
http://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=71