Fast ST7735 Arduino Display Driver - orig. from Adafruit
The PDQ library does not work in arduino projects that use more than one file, and the original Adafruit lib was incredibly slow.
I took a look and part of the problem is that for every pixel drawn for bitmaps, the SPI connection is reset. Correcting that gave me a tremendous speed boost, and along with that I added the ability to draw 256-color BMPs.