Our oldest laptop has become incredibly slow in the past while, and I'm wondering about some possible reasons. For example, I'll click on something and sometimes it will take several minutes for something to happen. The pointer will move around just fine and there's rarely the spinning beachball. It has two 4GB third-party RAM sticks, but the system report says their status is okay. Could this be the sign of a dying hard drive or just the result of being nearly 6 years old? Maybe El Capitan just doesn't work well with the hardware? Any ideas would be appreciated.