A lagging PC is the result of a number of system issues, such as data corruption, bad files, low disk space, and bad software. You can use a few Windows tools to speed up a slow computer. Do a little backtracking to find the problem.
Run Disk Defragmenter
Press the Windows button. Click "All Programs" and open "Accessories".
Right-click "Command Prompt". Choose "Run as Administrator".
Type "defrag X: -v" in the prompt, X representing the letter of your hard disk. For instance, if you want to defrag drive E type "defrag E: -v" in the prompt. Press "Enter".
Wait for the defragmentation to complete. Reboot your system once it is complete.
Run Disk Cleanup
Press the Windows button. Type "Disk Cleanup" in the "Start Search" field. Press "Enter".
Click "My Files Only" when the Disk Cleanup Options prompt appears.
Choose the drive and click "OK". Allow the tool to scan for possible space to free up.
Place a check by the files you want to delete. Click "OK".
Click "Delete Files" when the "Are You Sure You Want To Permanently Delete These Files?" prompt launches.
Scan for Harmful Software
Press the Windows button. Click "All Programs" and open "Windows Defender".
Click the "Scan" option toward the top of the window.
Choose the repair option once the scan is complete. Reboot your system once the repair is complete.