For GLViewportMorph, it takes ~ 9ms to render a frame + blit results
to system memory:

| canv |
canv := Display getCanvas.
[ 1000 timesRepeat: [ self drawOn: canv ] ] timeToRun

9714

if i disabling blitting to system memory, then the above loop takes
789 ms
 < 1 ms per frame

Drawing a system window morph with 600 at 400 extent (an outer morph ,
which is a little bit bigger than GLViewportMorph which sits inside of
it):
4327

~ 4ms per frame
(its just fills the rectangle with constant color)

For the same window on pharo it takes just 1393 ms.

Scaling a system window (along with GLViewportMorph) to 1200 at 800

GLViewportMorph + blit to system memory  - 24611 ms
GLViewportMorph w/o blit to system memory  - 754  ms
SystemWindow -  12351

so, with increase of drawable area by 4x factor,
rendering times not changes.
blitting to  system memory is 2.5 slower
and drawing a rectangle is 4x slower - a worst result showing an exact
linear dependency from covered area.


-- 
Best regards,
Igor Stasenko AKA sig.