So to me the scores on that chart doesn't really tell me how much load there is on the system. I like to see ram/cpu usage while different AV is running. off to find that chart.. I use defender with LTSB by the way. The only time I notice it running is during full scans just because my fans speed up a bit.
On my system (X99 5820k with 16gb@2666mhz) Windows Defender uses 180mb and about 25-30% cpu usage while running full scan.