If your Windows system has slowed down and isn't speeding up no matter how many programs you uninstall, you should consider reinstalling Windows. Reinstalling Windows may often be a faster way to get rid of malware and fix other system issues than actually troubleshooting and repairing the specific problem.

Does reinstalling Windows delete everything?

Although you'll keep all of your files and software, the reinstallation will delete certain items such as custom fonts, system icons and Wi-Fi credentials. However, as part of the process, the setup will also create a Windows. old folder which should have everything from your previous installation.

Is reinstalling Windows harmful?

Nope. It is nonsense. Frequent writing to a sector might wear that sector out, but even on spinning disks that is a slow process. A few hundred windows reinstallation to the same place on the disk will not be enough to cause a problem.