Alikhan
3
There’s a known bug with the full scan staying stuck at 0% for a while (rootkit scan taking place)… eventually, say in some extreme cases, it takes more than a hour and a half to make it 1%. Once it has reached 1%, the scan usually completes quickly and the percentage moves quicker.
You also need to take into account that if it’s your first full scan (that includes a first full scan after a clean install) that Avast! is populating the cache thus further scans will run quicker.