ST7735 display with esp32
The ST7735 uses SPI to communicate. It will always be slow compared to parallel connected screens.

The fact that you appear to be using bitbanged SPI (manually toggling IO pins) makes it even slower.

The fastest you will be able to get with that screen will be to use hardware SPI instead (which most likely limits which pins you can use - I am not familiar with the ESP32 though) but that will still be somewhat slow.

If you want really high speed screen updates then you will need a parallel interface screen, ideally a 16-bit parallel interface screen. However, for that you need around 20 IO pins to drive it.