I had issues with browsing starting last week on a PC running Vista 32 bit. Random web sites would either hang or not load at all. After eliminating browser issues I started turning off startup items. I finally eliminated everything except Avast.
I found that just turning off Avast web shield and even all shields didn't entirely fix the issue. I could not disable Avast from starting using msconfig or CCleaner. It would just turn itself back on. Finally I uninstalled Avast completely. That fixed the issue. I have Avast on 3 other Windows 10 PC's and have not seen the browsing issue.
I won't install Avast again on the Vista machine until this issue is fixed.