I run a iMac that I bought in late 2009, running OS 10.12.2. For some time the dreaded beach ball has been spinning at almost all clicks. I've taken it in to local Apple people, first, the HD is ok. and it seemed to improve, but then the ball came back and at times, after multiply impatient clicks it would freeze, and I had to hold the rear buttin to shut down. After the second trip to the shop, they seemed to think that the latests OS does not function that well on a machine this old. I have learned to click only once, and just wait out the delay. Question: does the opinion that the latest OS does not fun well on a 7 year old machine make sense? If the consensus is yes, would remounting the previous OS get me back to better performance?