frame rate drops when going to maximise

hi all, when i go to maximise on play the frame rate is about a third of what it is when playing in editor window. it goes from 105 in editor mode to 35 when using maximise on play.

is this normal?

the GPU is about the same but the cpu is twice as slow when on maximise. how can i check if unity is actually using my nvidia GPU instead of the onbaord graphics?

thanks

paul uk