Olympus E5 setting for shooting flight bird

hi, my name is arief..., recently i bout ZD 300mm f2.8 and couple of TC, i wonder why the AF perform not fast enough especially when i want to take picture of bird in flight. please help my find the right setting..

my setting usually i put C-AF + MF with foucing point on the center, C priority setting : on and i use full burst mode..

thanks
arief