I have a Mid-2012 15" MacBook Pro. Processor is 2.3 GHz Intel Core i7, 16GB of RAM, and a traditional HDD (a Hitachi 5400RPM Apple put in there after the original drive failed). For a couple of months, I've noticed that it is sluggish, specifically pausing (or showing the beachball) for 3-5 seconds between simple tasks, such as selecting a link in Apple Mail, switching applications using command-tab, switching windows in MS Excel, etc. This occurs with only a few apps open. (Just now the beachball came up for a few seconds when I selected the Apple menu to double check the specs on my machine.) I've checked Activity Monitor, and CPU usage is low with no unexpected processes, and RAM usage rarely gets up to 12GB, and that's only when I have lots of Safari tabs open. I used Disk Speed Test from Black Magic, and the results are 79.5MB/s write and 83.8MB/s read. Disk Utility and the Apple diagnostic tools both detect no problems. Since I'd like this old friend to stay with me at least another year or two, I'm thinking of getting an SSD. My question is this: is the SSD a reasonable next step to speed things up, or should I do something else first? From what I read, an SSD would be a worthwhile investment in speeding my MBP up, but I'd be really bummed to spend the money and see little or no improvement.