Possibly your computer has slowed due to the many updates over the years (assuming it is a Microsoft system). I'm thinking the fix you need is updating the operating system.
My 7-year-old desktop was very slow until last summer. I did use Revo Uninstaller when removing programs, but didn't uninstall many because what I loaded was usually what I wanted. Had two separate hard drives in it (not partitioned), one for the operating system & programs and one for my 'stuff'. So, basically, this old WinXP computer was well-managed over its years. But it still bogged down and chugged through its daily chores.
Last summer I upgraded it to Windows 7 by reformatting the drive with the operating system and then reloading the programs. Wow! Fast machine again. Not as fast as my new 64-bit Win7 with 32 GB RAM desktop, but darn impressive.