I had planned on living happily ever after without a virus tool on my DAW (as it used to be offline and files passed thru other protected machines). then the online update madness started, nextwin10 forced the Defender upon us ...
 
For some reason I don't trust this Defender in terms of effectiveness and I'm not sure it does not cause some random negative side effects to DAW functionality as it seems to kick in the background whenever it feels like and so far I have failed to find the settings to customize it.
 
Thinking about replacing it with some free antivirus, which is less intrusive (e.g. Avira AntiVirus) - thoughts, suggestions?

defender here, no issues, settings here https://www.google.co.uk/#q=windows+defender+settings

i use avast, works great, fairly transparent

I've been using the Microsoft Defender or earlier Microsoft Security essentials since Vista days.  I had been using 3rd party AV but was having problems in Sonar/Vista  Sonar support advised some 3rd party AV's could affect Sonar.  I switched to the Microsoft and my problem went away.  I also use Malwarebytes (paid version). 

Compared to most third-party offerings Windows Defender is pretty light on the system and relatively (very) unobtrusive.

Defender here.. since Windows 7 (skipped 8), running 10 now.

I'm with Fireberd. I use Defender and Malwarebytes (paid) and never had an issue.

I used Avast for years and then switched to Defender because I find it totally adequate. If you're worried about it interfering with your music production then just add all of your related music folders (Cakewalk, VST's, sample libraries etc) to its exception list.

pwalpwal
defender here, no issues, settings here https://www.google.co.uk/#q=windows+defender+settings

thanks. right there in my face and not seeing it ... now excluded all Sonar files, projects and sample libs. will keep using and see ...

tlw
Compared to most third-party offerings Windows Defender is pretty light on the system and relatively (very) unobtrusive.

That's why I finally stopped paying for annual updates for 3rd party solutions (Trend Micro for years, and then Kaspersky for years; Norton/Semantec is worse than any malware or virus you'll ever get).
 
I still run an ad blocker though (Adguard). It works well and doesn't seem to cause any issues with SONAR.