Maintaining your computer for optimum performance will require a little bit of time on a regular basis because:
Files can become fragmented taking longer to load and execute
You've just about filled up your storage area and need to either backup files or delete what's no longer needed
The Windows registry becomes cluttered. This slows your PC as Windows looks for what's no longer there.
The windows startup routine can be pruned to speed boot up
Web browsing data needs to be removed frequently.
Malware needs to be removed regularly
Full Anti-virus scans should be run periodically. These may take up to several hours depending on what you have on your machine.
You didn't keep your PC clean. PC's need regular cleaning inside and out to keep them dust free.
Allow about an hour and a half for me to bring you up to speed with keeping your computer running at it's best