Eric has an old HP laptop that was lagging and slowing down. He replaced the hard drive with an SSD, but it still lags. Leo says it's possible that if Eric reinstalled a backup of Windows, that there's malware or some corrupted drivers that is the original cause of the lag. The best thing to do is install a fresh copy of Windows and start all over. That means backing up data, then format the drive, and installing Windows from a known, good source. NOT a backup. Then restore programs and data and see if that works.
Joy has a 2012 13" Macbook Pro. Is it worth it to replace the hard drive with an SSD and boost the RAM? Leo says it's worth it ... if you want to do it. It'll require a special tool, but you can get that at OWC. And OWC will have videos showing you how to do it. And the boost in performance will be huge with an SSD drive. It'll cost about $200 to do it. But if you like to tinker, it's a great little project that's easy to do.
Another place to research how is at iFixit.
Richard wants to get an SSD for his laptop. Leo says that some laptops are upgradable and some aren't. Leo recommends going to iFixIt.com. They have tips and tutorials on how to work on laptops, mobile phones, and a wide variety of computers. If anyone knows, it's iFixit. YouTube is also a great place to find out how to do that.