Hi Claudio,
Welcome to Microsoft Community. If your Surface tablet is running slow, here are a few steps you can try to help improve its performance:
Force a Restart Press and hold the power button for about 20 seconds until your Surface shuts down and you see the Windows logo. Then release the button this can help clear temporary glitches.
Run the Surface Diagnostic Toolkit This tool can automatically detect and fix common issues. You can find it here: Fix common problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support
Check Your Power Mode Settings If your device supports it, click the battery icon on the taskbar and adjust the Power Mode slider to either Better performance or Best performance to give your device a boost.
Additional Tips Microsoft also has a helpful guide with more suggestions here: Tips to improve PC performance in Windows - Microsoft Support
Let us know how things go after trying these steps we’re here to help!