Mark has two Windows 10 computers, and they're both starting to lag, especially when opening apps. Leo says that usually indicates a hard drive issue. The drive is starting to fail, and the computer keeps trying until it gives up. It could also be the app itself causing lag. But generally, it's usually a hard drive issue. Leo suspects if he replaces the hard drive, it'll speed up. Especially if he gets an SSD. Look in the task manager and see what's hogging the processor. It could be Windows is indexing, or it could be malware.