My testing on the K3 eink displays shows that dithered black and white has max speed about 5 FPS for 800x600, but up to 12 FPS for a smaller partial update. For max speed, you could display a full grayscale image of an arcade machine, with a smaller 400x300 (or so) window with only black and white partial updates inside that window.
For a 12 FPS example (which also demonstrates eink driver "deferred write" time-domain artifacts), try my "vidtest" program on the K3. You can download it here:
https://www.mobileread.com/forums/sho....php?p=2012359
The download contains only binary executable. The C source code contains mostly commented-out code for testing out stuff, and is not ready for publishing, but I could provide it anyway by PM on request (if you promise not to complain too loudly)...
