It seems to be inevitable that a computer running a Windows based operating system will slow down over time.
There may be numerous reasons why your computer behaves badly and is no longer the speed demon it once was. Simple maintenance, practiced regularly, which is easy even for a non-expert, can keep your Windows based PC running smoothly at peak performance for years.
The most common problems that have impact on a computer's speed and behavior are listed here, with the appropriate free software solution. This is not however, an exhaustive list.