Knock code/On slow response topic

after 2 months of usage i'm facing this slow responsive of Knock code/On unlock. Previously it was very quick. but now it almost waste 2-3 seconds to unlock the device. I disabled Knock code but still the screen turning on after 3 seconds to the double tap. I'm on Cloudy G3 1.2, device LS990.
Does anyone know what has happened and any way to fix this?
Thank you!