TairikuOkami

Level 23
Verified
Content Creator
You can try this for a deeper cleaning. Download and run as admin [Batch] Windows Cleanup - Pastebin.com Or try software like:
 

redsworn

Level 3
Verified
There are many things which can cause PC slowdowns. Malware, dying disk, poor drivers, corrupted updates, and so on.

How long it's been happening? Have you scan your system using malware scanner? Have you check your disk health using Harddisk Sentinel or similar tool?

Check CPU & RAM usage and disk activity via task manager. See if there's any abnormality.
 

LoLs

Level 2
You should mention about your PC configuration first., or you can share config here Computer Specifications

I'm newbee, but from experience, for windows 10 it's better to use SSD, you will never facing slow performance anymore., at least for me. :)

Anyway my brother have slowdown issue on his old laptop couple years ago,. sometimes its get bluescreen, and slow startup loading, and even shutdown took some times. He been using that laptop like 24/7 lol. And i heard tick tick tick sound,.. so after change it to SSD all problem gone,.. its seem the old HDD just about to die. I remember he's so happy after using ssd lol, ~almost 3-5 minutes boot time before and took only few sec / less then 1 minute after using SSD.
 

Imranmagic

Level 2
One more thing i want to say that slowing PC may be you have installed PUPs software program because PUPs also slow down PC