Hi Adriano Brandini Celli,
Thank you for reaching Microsoft Community.
I understand that you are having issues on your Surface Pro 8 where it has a high CPU usage causing slow performance and also, the Surface get warm until it crashes.
Just to clarify though, when the Surface heats up, does it show you a thermometer icon? or it shows a bluescreen error instead? If it is a bluescreen error, may I know what error code or message does it usually show? If possible, provide us with a picture of the error.
Also, please provide us also with a screenshot of the Task Manager window of the device showing the Processes tab.
If you are not able to attach photos on your reply here with us, you may instead upload the photos on OneDrive then just provide us here with the Shared Link. See this page for reference: Share files with OneDrive - Microsoft Support
For now, please check the Surface drivers' health through the Surface app, run the Surface Diagnostic Toolkit to run some system checks and repairs and check for updates in Windows Settings > Windows updates to make sure all updates are installed including Optional updates. See this page for reference: Fix common Surface problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support. After running those steps, see if the behavior of the device improves.
Kind regards,
Marrion