Many antivirus programs, like avast!, run as soon as Windows launches. Some startup programs are required at startup -- like system processes -- but others can slow Windows down, increasing the time it takes for the operating system to load.
If your computer lags after booting to Windows, disabling avast! on startup can improve the speed of the operating system.
Press the "Windows" and "R" keys at the same time to open the Run dialog box. Type "msconfig.exe" into the dialog box, then press "Enter" to launch the System Configuration window.
Select "Startup" and then click the "Startup Item" button to alphabetize the startup applications.
Locate "avast!" or "ashDisp.exe" in the list of items. Uncheck the box to the left of the application to disable it from running at startup.
Click "Apply" and then click "OK" to close the System Configuration window.