I have been using Avast with very great success - until updating to version 8. Now my system is sluggish, and internet access/browser performance is very slow.
My connection speed before the update was ca 20-23Mbps. After the upgrade, it regularly clocks in at 8-10Mbps.
As a test, I uninstalled Avast. General performance was very crisp and speedy. I checked my connection speed at it was ca 28Mbps. I then tried MS Essentials. That clocked in ca 18-2o Mbps.
Not being entirely confident with MS (again, Avast has served me very well) I reinstalled Avast 8. Once again, poor performance and slow connection speed.
As was the case with v6 and v7, I selected the default installation initially. The 2nd install I chose minimal. Same result: crippling performance.
I agree with you, my internet speed becomes very slow when I install Avast, although I use Pro version with no firewall, “website not responding” appears very frequently.
Same here with an new install on a new computer. When I start the computer and check the download speed the speet is 1-2 Mbps. As a solution I turn off the shields for 10 minutes and check the speed again 30-35 Mbps and turn the shields back on. As a result the internet speed stays at 30-35 Mbps.