On all my systems I only have Windows Defender having removed McAfee from all of them once I unpacked them from the boxes Been using Defender now for nearly 2 years and have had no trouble at all with any web sites I scan when it notifies me and it updates on its own I have found since using it all my laptops start up and load very fast
Its still better than the other 2, although, I too have been having issues with avast (I didn't have the problem when I first had win7), there is still Malwarebytes, comodo (which I was using for a long time)....