system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do computers get slow?

And how can I prevent it?
gpt
It can vary from computer to computer, but its usually a combination of a few things:

* Startup processes - the more you install over time, the more that runs in the background

* Wear and tear - over time you may lose performance as the hardware itself ages, especially with hard drives

* malware - bad software is bad, and will cause a lot of problems over time

* Driver issues - drivers are instructions for your computer. Out of date drivers can cause your computer to be pretty inefficient.

A simple analogy is this:

You start out a lean, fast, runner. Over time, you start adding things to your running regiment. As you add things, it takes you a little longer to get out the front door. You get out eventually, but maybe it takes you 1 minute instead of 15 seconds.

Since you've got these other things on your mind, when you try to do things while juggling, sometimes it takes you a while. Normally you can run and wave to the neighbor within 30 seconds of leaving the door, but now you have that morning weather software and the news software that slow you down a bit, so you don't get a chance to wave until about a minute out the door instead.

You try cleaning up your regiment with some new techniques(new drivers) so that you do your regiment more efficiently, and that helps a little bit here and there. Some regiments run better thanks to your new techniques, others aren't effected - some might even be worse than before. But you take what you can get.

One day you end up getting sick from a virus, and *everything* goes to crap. Your running slows down, you have a hard time trying to wave to the neighbors, and some days you can't get out the front door.

At that point, sometimes starting fresh can help - you strip yourself back down to your basic new-runner state, (reformatting), and go from there. But its been a while - your joints might not be as good (hardware getting older), so maybe you need 30 seconds instead of 15. Still better than where you were though!