Virus (and adware, malware) scans take a long time.
They check against every definition for every file in your computer - unless you whitelist some types or limit the folders it scans.
AFAIK any and all AV will take a long time. They may have different interfaces and different definitions, but they all do basically the same thing.
It isn't something you should need to do while sitting there watching its progess (boring :yawn: )
But for it to do it's job you do need to let it do it's thing.
Start the scan when you know you won't want to be on the computer for a while eg. going to sleep for the night.
Defrag also takes a long time, but this too is important to do once in a while