1. Overheating
To prevent your computer from overheating, consider using a cooling fan. Excessive heat can negatively affect your computer, reducing its performance and rapidly shortening its lifespan.

2. Dust buildup
3. Virus infection
4. Low RAM
6. Fragmented hard drive
A fragmented hard drive is another common reason for slow computer performance. To resolve this, you should defragment your hard drive. First, go to the Start menu, open Computer, right-click on the C drive, select Properties, then Tools, and click on Defragment Now. While the process is running, avoid using your computer. The duration depends on the size of your hard drive and the level of fragmentation.
7. Excessive Fonts
Another often overlooked factor that can slow down Windows is the number of fonts installed. If you're not a professional designer, it's best to stick with standard fonts like Unicode or Vni to avoid unnecessary system slowdowns.
8. Too many unused files
You should regularly clean up and delete files you no longer need. Over time, unused files take up valuable space on your hard drive and contribute to your computer's sluggishness. If you can't bear to part with some files, consider storing them on an external hard drive. This will free up space on your computer while preserving those important files. Additionally, you can use the built-in Disk Cleanup tool to find and delete junk files, which will increase the available space on your C drive and improve system performance. To use it, right-click on the drive, select Properties, and then click Disk Cleanup.
