What email client are you using?
If you only use Outlook Express, you can stop (or even remove) the Outlook/Exchange provider.

I don’t know where you got those memory usage data from, but if it is from the taskmanager… Don’t trust it. It is not reliable.

ashserv.exe is part of the on-access scanner.
ashmaisv.exe is the mail scanner.
ashdisp.exe shows the blue ball.
ashcmd.exe is the command line scanner (Pro version)
aswupdsv.exe is the part that checks for updates.
ashQuick.exe is Avast’s quick scanner.