My laptop is running slow, what can i do to fix it?

A not really uncommon cause, alas, is bad hardware (especially a hard disk with too much errors), or just a slow hardware (slow processor, not enough RAM).
But, indeed, software is a more common cause. Why do you think it's that?

I'd start with a malware check, as told in https://www.cnet.com/forums/discussions/how-to-remove-pup-option-603542/#post-f742c795-5881-433b-a29b-6d758efe5cd3 . That might help. Or just as well, it might not.

Then note that crap that doesn't run, doesn't harm the performance. So concentrate on the applications that you see running in Task Manager. Start with the 5 processes that use most CPU. What are those?

If you can't find anything strange, go back to factory conditions. Then the laptop will be as fast as it was when you bought it new. If that's not fast enough, it's hardware. Then - if no obvious cause such as a bad hard disk - it might be time for a more powerful one, or more RAM or an SSD.