Why does a computer slow down?

Many reasons and the list are long. There could be a startup overload, registry errors or mismatch, a bad hard drive with a bad sector, security software corruption, uninsulated programs, a corrupt operating system, missing DLL files, viruses and ITD, hardware problems, not enough memory and CPU maxed out. Many problems can be easily fixed but others are a bit complicated. Increase your productivity with a tuned up speedy computer