latitude 7480 keyboard input lag

i have a latitude 7480 and my keyboard started slow responding when i type like if i try to type normally it skips letters, like if i try to type the ward "keyboard" with normal speed this is the result "kebd" but if i type slowly like 1 letter per 2 seconds it types fine but i cant do that cuse its too slow. resetting bios settings to default seems to solve the issue temporarily but its goes back after some time and yes i did update my bios to latest version ( Latitude_7x80_1.25.0 ) and trying safe more and reinstalling the drivers and all of that but nothing works plz help