Hi
I am on a Winxp pro SP2, Compaq Presario 2100, 1.8 Ghz, 192Mb RAM.
When Avast has its system tray icon, it takes AGES to startup. For this reason I removed the icon from startup and now it doesn’t take as long.
Is there any reason for this?
Thanks
Which is your sensitivity level? I mean, is Standard Shield at High or Normal level?
avast takes more to load if you have more programs autostarting after boot.
Try Startup Delayer to control the startup order of the programs.
You can set some applications to start very after the boot (logon) itself. 
Removing the icon doesn’t remove the underlying scanning process or services, just the interface. So I’m somewhat surprised that you see any difference. I guess I will have to check that out.
Do you have any other security programs running at boot?
What is your firewall? - mine has a plug-in that scanned upwards of 1000 files and these were also checked by avast because they were being opened. Solution disable the plug-in as avast was providing that cover.
As Tech mentioned the Standard Shield sensitivity can have a dramatic effect on boot time.
I would also check for programs that start on boot by default that you don’t need immediately on but, such as many media players want to start on boot, you only need them when you want to listen to something.