Can one prevent Antimalware Executable to start hogging CPU for extended periods each time some network adapter gets active?

One of the most annoying habits in Windows 8 is, that the built-in "Antimalware Service Executable" (part of "Windows Defender") starts hogging my device's CPU with 60-70% (and 100% disk) for extended periods EACH AND EVERY time after I wake it up.

I wouldn't mind if it starts doing its business IN THE BACKGROUND but when I wake my device up from standby it's usually to get something done NOW and thus I find it increasingly unacceptable, that the system is always taken over by Window's defender exactly then and for up to several minutes! If I don't find a solution soon to throttle this beast, then I will disable Defender altogether!

What I noticed is, that this process seems to be actually triggered not by the system waking up, but by the network adapter becoming active. And actually, this happens each and every time ANY network adapter gets active! E.g. if my system has NO network connection at all and I plugin the network cable the Antimalware Service Executable starts. When - after it has settled again - I additionally enable Bluetooth then the Antimalware Service Executable starts its hogging business again. And if I then additionally enable the WLAN a few minutes later, it will AGAIN start to consume CPU!

So: can one decouple this? Running a scan ONCE after (re-)starting it is definitely enough, especially if Defender hasn't downloaded any new signatures since the last run! And, second, can one make Defender convince to strictly run in the background ONLY?

Michael

[Moved from Windows]