I switched from AVG to Avast for awhile, but got very annoyed with the damn software flapping it’s gums like a petulant kid, telling me it had upgraded the definitions or whatever. Sometimes I leave my speakers on and I absolutely hate any software that talks without being axed ... so it had to go bye bye.
Back to AVG, which works fine for me, and does NOT slow my machine down at all (quad core with 4 gig ram)
You do know you can turn off the audio on Avast, right? It’s right there in the preferences. I have had both AVG and Avast, and have found Avast to be slightly easier to operate and less intrusive. They are both very good, especially since they are free.