Full virus scan taking long

Hi.

I am new to the forums but have been using Avast for a long time.
I am hoping someone can assist with an issue I am experiencing.

I have run a full virus scan two times, once last night and another this morning.

Last night the scan was stuck 87% for some time so i left my laptop overnight, thinking it would complete overnight. However this morning it was still stuck on 87%. So i cancelled the scan, rebooted and ran the scan again.

In about 30/45 mins it got to 96%. And then it seemed to stall again. So I left it for another hour and in that time it only moved 1% to 97%. At this point I cancelled the scan.

It seems Avast completes most of the scan with 30/45 mins and then stall for hours with the last bit. I am not sure why.

Previously full scans have not taken more than an hour.

Also the smart scan works with no issues - takes a minute or 2 to complete

Relevant info

Windows 10
128GB SSD - about half full so not much data on the laptop.
Avast settings are all on default

I’d appreciate if someone could assist with helping me find out why the scan is taking so long.

Thanks in advance

Muhammad