Behavior Shield slow on Fat32 partitions?

Avast Free Antivirus / Premium Security
1

Behavior Shield can still cause mysterious slowdowns in 5.1.889 (a Windows 2000 install), but seemingly only for files located on a Fat32 partition!

A good test case is this AOL installer, http://download.newaol.com/aacd/AOL%209.0%20VR.exe

The executable is a WinZip Self-Extractor. Without Avast it starts instantly, then takes about 6 secs to unzip. With Avast it takes 3 secs to start and 9 secs to unzip if the file resides on the C:(NTFS) partition – not bad. But mysteriously, if this file is located on the D:(Fat32) partition, it takes 23 secs to start and 81 secs to unzip.

The Fat32(?) slowdown disappears if the Behavior Shield is off, or even if just the “unauthorized modifications” part of BS is unchecked.

2

Yes, I can confirm that this is a known issue that is already fixed in our internal builds and will be fixed in the upcoming avast version 6.0.

Actually, it would be great if you could test the avast 6 beta and verify that it fixes the problem even in your scenario.

Thanks, and sorry for the inconvenience
Vlk

3

Beta 6.0.945 does eliminate almost all differences between running this AOL installer from C:(NTFS) vs. D:(Fat32) – thanks.

But you should know that Behavior Shield will still report 1 “event analyzed” when this installer is launched from the D:(Fat32) partition and 0 “events analyzed” when launched from the C:(NTFS). This leaves a persistent launch time difference of a couple of seconds.

There are no “events analyzed” during the actual unzip anymore, whether run from C: or D:

There are no “suspicious events” in any case, as I believe was true under 5.1.889 as well.