@moniex.
I assume you have launched a Full Scan. Depending on size of disk and number of files to be checked, this can indeed take some hours. Also the 30% indicator may not be linear. Sometimes it sticks at a percentage then jumps to another. There is no pause button anymore Avast scans, should you need to interrupt it, so just let it run to completion.
Once you have completed the Full Scan, you should not need to another again on a regular basis. Just allow the active shields to provide necessary real-time protection. I only run a Full Scan once every few months or if something is not right.
