Urgent: PC Repair for Slow Performance

My PC has been running incredibly slow, affecting all programs and applications, from web browsers to office software. I've already tried several troubleshooting methods including restarting the PC, running antivirus scans, clearing cache and temporary files, and even performing a complete Windows reset. Unfortunately, none of these solutions have worked. I need an expert who can diagnose the problem and provide a solution to speed up my PC. Potential experience with hardware upgrades, software optimization, and general PC repair would be a plus.