Please be assured and to resolve "Device lagging issue" kindly follow the given below steps:
1) Check device cache: Settings>Device care>Storage>Clean now. For a particular application: Settings>Apps>Pick the app that you like to clear off the cache memory. For example 'Samsung Internet' >Storage>Clear Cache.
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.