Chosen Solution
I was asked to repair this MBP, because it was very slow in responding to mouse or trackpad clicks,as well as keyboard input, if at all. I replaced the old HDD with a good SSD fresh install Sierra, and she was fixed. Until I demonstrated my fix to my friend, when it suddenly was again slow in responding to trackpad etc. So I decided to dig some further, but now cannot even reproduce the problem. She is running fine now for hours, even ran “Heaven” without issue. So I can rule out the dreaded 2011 GPU failure, right? How do we go about tracking an intermittent issue? I do not have the ASD for this rig, unfortunately…
I’d recommend opening up Activity monitor when the glitch happens and check if anything unusual keeps the Cpu busy with something. Have a look at battery condition too.
