Windows 10 PC getting slower every month

Check the drive's health too, not only the free space. A hard drive or SSD that's starting to fail slows down gradually long before it dies. CrystalDiskInfo is free and gives you a simple Good / Caution / Bad. If it says caution, back up first and worry about speed later. Also, Windows 10 stopped getting regular updates in October 2025. It still runs, but it's worth deciding whether this PC moves to 11 or gets replaced before you put a lot of time into tuning it.

Is it still on a hard drive or an SSD? If it's a spinning drive, that's your answer, and swapping to an SSD does more than every tweak below put together. Otherwise work through it like this: 1. Task Manager > Startup apps, disable everything you don't need booting with Windows. Updaters, chat apps and game launchers pile up here over months. 2. Keep at least 15-20% of the C: drive free. 3. Task Manager > Processes, sort by CPU and Disk while it feels slow and see who's eating it. 4. Go through browser extensions, they add up. 5. Run a full scan with Defender to rule out anything nasty. If it's still slow after all that, back up and reset Windows.