Faced with a slow Pc- constant installation and uninstallation of software

I have a fairly decent PC configuration but today I am faced with a slow processing. Given that I am not the only family member using my PC, I usually find redundant software and I have to clean up on a regular basis. I heard that the frequency of installing and uninstalling software have an incidence on the speed of the PC in general. Is that true? Can anyone enlightenment on the purpose and impact of registry files
