system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do computers get slower the longer you have them even if they aren’t damaged?
gpt
Marginally they do get slower as you install more programs that want to keep running and as temp files and such build up.  But that sort of slow down is minor.

The feeling you get that your system, which used to be super speedy, is now chugging along is more that over time the software released keeps asking more from the hardware.  Windows gets more features, games want more cycles for logics, Word needs a GPU now so it can have pretty toolbars, etc.

So really the machine is just as fast as it was, the programs just become more demanding until it can no longer keep up.

Of course, sometimes you will have just installed terrible stuff that's eating all your processing but that's more of a virus / malware situation than normal "aging".