|It would help to know your system specs & whether you're asking about a desktop or laptop.|
"My PC keeps getting really warm and runs slow"
Adding a couple of comments to Fingers' list:
7 - if you have a desktop, shutdown, unplug the power cord, open the case, & blow the dust out of the CPU heatsink & cooling fans. Do NOT use a vacuum. If you have a laptop, blow the dust out of the cooling vents.
8- download & install CCleaner-Slim. Run the Cleaner & remove everything it finds, then run the Registry scanner & remove everything it finds. Reboot the system, then run them both again. Also, if you click on Tools > Startup, you'll find a list of all the programs that load at startup & run in the background. Most likely, very few of them are actually necessary. Disable or delete the ones you don't need/want.