Installed programs don't slow a computer, at least not unless they are badly
written and damage Windows itself.
Slowdowns are more often due to memory-resident junk, most of which is
visible as an icon in the system-tray at bottom right. Digital cameras,
scanners, etc are notorious culprits for installing trash of this kind.
Open a Run box and type 'msconfig'
On the far right pane of the multi-tab, you can see the processes which run
at startup. Generally it's quite safe to disable them all, and do a test
reboot. If it turns out some are needed, the process is reversible. Don't
disable any which relate to your antivirus software, of course.
BTW, what antivirus are you using? If it's Norton, that will take 50% off
the performance of the computer in one go.