But there are scenarios where other more complex issues might be affecting your Mac. In most of these cases the problem can be solved by simply opening the Activity Monitor utility and looking for the process that’s taking more CPU than usual. – Your Mac slows down or its fans start spinning wildly without reason. – Some apps become unresponsive all of a sudden. Some common symptoms of your Mac not performing OK are: However, even though Macs are far more reliable in this respect than Windows PCs, they still tend to start behaving weirdly from time to time. Keeping a Mac tuned up tends to be a fairly easy task.