Processors and HW don't just go weak.
I would think it's more of OS and software problem. Check if your CPU is firing on all cylinders (cores) and reaching full frequency. Check drivers for everything and if there are some things running in the background. Also check for mallware.
If nothing helps, backup your files and do a clean install of OS making sure you install all proper drivers.
Do I need to have copies of my drivers on a drive or something before I clean install? I don't have a cd drive and even if I did I'm not sure I would have the cd's anymore. I've checked for malware and have updated my drivers but I suppose the clean install would probably be a good thing to try.