Slowdown with excess draws

[Feksaaargh]

When drawing many times to the screen using Pinetime::Components::LittleVgl::FlushDisplay, Infinisim slows down greatly. This appears when there is in the order of several tens of draws per frame.
I've created an example app which shows this here: https://github.com/Feksaaargh/InfiniTime/tree/infinisim-draw-slowdown. This example has 50 5x5px particles, each of which are blanked out and redrawn every 40ms for 2500 draws per second.

infinisim_recording.mp4

watch_recording.mp4

[NeroBurner]

This is most likely because of https://github.com/InfiniTimeOrg/InfiniSim/blob/main/sim/displayapp/LittleVgl.cpp#L318 which I introduced to slow down the display transitions to have them look comparable to how they look on the PineTime

  // delay drawing to mimic PineTime display rendering speed
  vTaskDelay(pdMS_TO_TICKS(3));

If you find a better way a PR ist most welcome :)