Dear Samsung Member,
Greetings from Samsung Customer Support!
We are very sorry for the inconvenience caused to you, please be assured and to resolve "lagging" issue kindly follow the given below steps:
1) Clear the Cache of your device (Settings >Device care >Storage > Clean now).
2) Reset the device and before resetting the device make sure to create data backup of your device via SMART switch mobile application or http://www.samsung.com/in/support/smartswitch pc suite.
Settings> General Management> Reset.
To resolve "Heating" issue please follow the below given steps:
1)Close background running apps.
2)Uninstall the unnecessary apps.
overheating--Follow the link for more details :- https://www.samsung.com/in/support/mobile-devices/why-the-heating-issue-occurs-in-mobile-device/
If the issue still persist, kindly register your concern in Samsung Members app (Samsung Members app > Get help > Feedback > Error report/ask question).
Note: Please send device log files within 15 minutes of issue occurrence along with the exact issue details.
Thank you for writing to Samsung.
Samsung Customer Support