Yes, you get the same speed as I did.
Bear in mind that Adafruit does not want to support STM32.
So they cripple the SPI. (except for RogerClark)
But no one in their right mind would run the RogerClark Core.
Adafruit cripple Teensy4.0 and 4.1 too. Look at the SPI_DEFAULT_FREQ conditional defines.
Did you try Bodmer's TFT_eSPI ?
David.