how to disable avast scan after boot up

Hello,
Every time I start my computer, it hangs for first few minutes. It seems avast scans the computer on startup and computer hangs. If it is so and avast do scans on start up, then how to disable the scan on start up? I am using avast free version.

It doesn’t start a scan as such, certainly not a default action. But it will be scanning other activity on your system, that is what a resident on-access antivirus does.
What avast version (number) do you have installed ?

Have you made any changes to the default settings ?
Have you made any other changes to your system recently (and on what OS) ?

If you can open the Task manager can you see what process is using the most CPU% ?