Until this morning I was a strong believer in using anti-virus software on my Macs. In particular, I’ve been using Avast Mac Security 2016. I just uninstalled it. The reason for this drastic move was the information contained in the following technical paper recently authored by individuals with impeccable credentials. I suggest you at least take a look at Figure 3, page 5 and read the Conclusions section
Already discussed in another thread.
Next to that, this forum is for support with Avast Free Antivirus / Pro Antivirus / Internet Security/ Premier for Windows.