A complete fillscreen in 125ms would have been perfectly fine, but that is not even near to what I get. You can easily follow the line of fex the black when a screen is filled from white and that takes around halv a second so 500ms+.
I might perhaps guess its the non working "#define STM32" that maybe is one of the reason since it just see the processor as a "generic" one which can't be something good for optimal SPI or any performance.