Hi,

quoted

fbcon could do the same, i.e. render to fbdev in a 60Hz timer instead of
doing it synchronously.

Hopefully only the parts of the screen which need a redraw?

Sure.  drm fbdev emulation with shadow framebuffer tracks changes and
only flushes dirty areas to the real framebuffer.

fbcon could do the same when implementing lazy rendering, keeping track
of the chars/attrs which did actually change and only render those to
the (emulated or real) fbdev.

take care,
  Gerd