Avast IS & Windows 7 - Slow Internet Connection Speed

Since installing Internet Security (5.0.594) I’ve experienced a big slow down in my internet speed.

I recently performed a clean install of Windows 7 (Home Premium) on my PC. I made no changes to the security settings in Win7 (Defender, Firewall, Malicious Tools). I tested the speed at 56Mbps (no applications installed other than what was installed from the installation disk). I then installed Malwarebytes’ Anti-Malware application. I retested and got 56Mbps. I then installed Avast Internet Security. I made no changes to any of the settings in AIS and my internet speed dropped to 18Mbps. What changes can I make to get my speed up to 56Mbps? Should I turn off Windows security settings or adjust them to make them more compatible with AIS? Thanks

(PS. I have not installed an email client yet - still looking for something smaller than MS Outlook.)

My PC: Dell Precision Workstation 340: Processor P4 (1.5Ghz); Ram 1.5 Gb

may be related, not sure.My guess is that AIS firewall could be messing with the web shield proxy, or just general internal traffic on Windows.
http://forum.avast.com/index.php?topic=61567

try turning off the firewall (in AIS) a minute and see the result…