I have a plasitic unibody MacBook.It had been my go to computer for a year or two. I handed it down to my wife after her previous Generation MacBook failed and was end of life.Two nights ago I updated her OS from Yosemite to El Capitan. Even though her computer has 16GB of RAM and 2TB of disk it’s performance is awful! Given that Moore’s Law suggests that CPU density doubles every year and by extension increased performance there is no justification for why her MacBook is so slow.Occam’s Razor suggests something completely different. Since operating systems are so very complex and thus standardizing hardware designs to make use of commodity manufacturing economics there must be a black ops department with Apple that intentionally breaks backward performance and speeds up end of life. As an example look at any of the popular Linux variants, Windows and ChromeOS. With few exceptions edge to edge versions do not suffer the sorts of performance issues that Apple consistently demonstrates.UPDATE: In a way I feel vindicated. This writer asks the right questions although I’m not sure where he gets the answers but they are inline with my hypothesis.