My game lags when the Home button is pressed while playing games in full-screen mode

When you press the Home button, the system is focusing on a secondary application. Due to the standard Windows environment, you will need to click back into the game. You can do this by pressing the Home button on the tablet itself, which is the simplest and quickest way. If you have a keyboard connected, press the Alt + Tab keys. If you have a mouse connected, simply click on the screen you want to focus on.