If your keys are sticky, try using an alcohol wipe to carefully clean the surface of the keys and then cover the keyboard with a silicon protector to prevent any more damage to the surface. For the slow response, there might be something underneath the keys that may be causing obstruction. To solve this, remove the keys and carefully clean underneath the surface or consider replacing the keys entirely. To do this, visit this troubleshoot page: Samsung ATIV Book 9 Plus Troubleshooting and see their repair guide:Samsung ATIV Book 9 Plus Keys Replacement

That happened to me too! Turns out the battery was completely ruined. I replaced my laptop battery and that fixed the problem. Take a look at this troubleshoot page Samsung ATIV Book 9 Plus Troubleshooting and also the repair guide Samsung ATIV Book 9 Plus Battery Replacement