The good news is that it is pretty fast, which no doubt is a result of the limited 84×48 resolution and 1 bit color depth. The bad news is that it's still a bit of a memory glutton, consuming 42% of program storage and 24% of dynamic memory. Most of that is probably the data for the lovely fonts.

The frame update time of 100 ms (the inverse of the fps noted in the source code) is respectable, and character change artifacts are not objectionable. The frame update time is expected to halve with a 16 MHz board, but there are no 16 MHz 3.3V boards, so that means you'll have to complicate things a bit with level shifters.

I used U8g2 to see how quickly a Nokia 5110 display could be updated with a 3.3V 8 MHz Arduino Pro Mini. The module came from an Asian source.

The glare on the edges is an artifact from the four LEDs used to backlight the display. In real life the arifact doesn' appear as glare, but it is clear on inspection that there are four sources of illumination.

video

source code