With Bitdefender, some system reserves are left, so it's possible to browse the news or write an email without crashing your system. Though, a downside is that when you're scanning with Avast, you pretty much can't do anything else with your device. The difference isn't as huge with quick scans, but Avast just performs a little better. My test unit has a relatively uncluttered 256 GB SSD drive, and it still took almost two hours. It takes about twice as long to complete a full system scan with Bitdefender as it would be with Avast. Where Bitdefender lags behind is in background scans. That saves not only your device's resources but your time as well. There are several tools that should help you avoid frequent scans. So, you won't be left with only the antivirus scanner and real-time protection. To some extent, the same applies to Bitdefender, however, the service has much better network safety tools even on its most basic version. So, potentially the amount of malware that you have to deal with will be significantly lower because most of the junk won't end up on your device. With the paid version, there is a much bigger focus on network protection. This is because Avast heavily focuses on frequent background rescans for threats that already are on the inside.
Avast's capabilities to protect you against malware will heavily depend on your subscription version.
