I use Windows7 32 and the latest free Avast.
I have a total of 35 processes on start up, 9 of them are Avast. Just wondering if they are all vital.
AvastUI.exe
aswToolsSvc.exe
AvastUI.exe 22MB
AvastUI.exe 7MB
AvastUI.exe 6MB
aswEngSrv.exe
wsc_proxy.exe
AvastSvc.exe
aswidsagent.exe
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Yes they are required in what is an on-access antivirus it has to be waiting in the wings so to speak. It may also depend on the Avast components you have installed.
Some of the duplication is to a certain degree, multi-tasking which speeds things up.
Rather than looking just at the number look at the resources used (see my attached image) the top part I expanded as these are basically the AvastUI entries, The others are below. Then just compare it with other processes, such as your browser (Firefox in my case has 10 processes running, multi tasking also) basically one for each open tab. This is using way more than Avast as far as resources used are concerned.