Most Windows users discover it with time: right after Windows is installed, or when one gets a new PC, the machine is “clean”. Startup and shutdown are fast, the system directories are not crowded with files that contain God knows what, no useless program is wasting your CPU 24/24, etc. Then, things start deteriorating…
Windows does not provide an easy way to keep its system clean.
For example, there are many different ways for a program to install itself so that it is run automatically, so it is not easy for you to track down which application decided “by itself” to use your system’s resources in the way it wants.

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