It stutters during streaming from any source. The source playing the video utilizes the greatest amount of CPU. Second is the activity monitor itself. Already brought the machine into Apple and we reviewed that possibility. At that time I was directed to restore the machine to factory settings as it may have been caused by the relatively recent El Capitan update, which I have done with zero improvement. I was told at that time that there may be a hardware issue such as my bluetooth card should the reinstall not correct the problem. Evidently I will probably need to send the machine to Apple for warranty repairs if this issue can't be resolved in this support community.
Ive also searched this issue in the community and have discovered a growing number of identical/similar circumstances affecting other member's machines with none being successfully resolved. So, I suppose i'm hoping for a miracle before I reluctantly release my beloved Mac.😊