Bitdefender is widely regarded as a decent programme, but my experience has been that it is a resource hog, even on a plugged-in desktop, and for that reason I haven't been a fan. It appears to be the same thing I've seen previously.
When I open my task manager, I don't see an Antimalware Service running. I use Defender, which comes pre-installed and is a Microsoft product, so there's no reason for me to install another anti-virus programme on my Surface. You must have installed Antimalware Service and Bit Defender, which I haven't seen mentioned or discussed here on this topic.