@ archdak
I take it that you mean a 40GB drive and not 40Mb that you stated.
You don’t say if this was a Quick or Full System scan or if there were any modifications to the scan, scan archives, PUPs, etc. that would contribute to the overall scan duration.
Some information on your system might help, operating system, CPU, RAM ?
I never use the displayed scan speed as it fluctuates, but use the data scanned and scan duration for my overall scan speed. I do a Quick scan with these settings (image) and with Heuristic sensitivity at High and Use code emulation. Last quick scan was 3min 3sec for 5.6GB, last Full scan, same basic settings but it scans all drives, 9min 34sec for 20.7GB. My system spec in my signature.
Have you run any previous scans using avast before installing avast 8 ?