Octave performance goals after 4.2

[Rik]

All,

It might be a worthy goal, after the 4.2 release, to look at improving
Octave's performance.  While messing with the 'o' marker changeset I put in
some printf statements and I was surprised to see them being executed twice
for a simple command like plot (1,1, 'o').  It seems like an easy way to
speed up graphics by 2X would be to draw the Canvas object just once.

--Rik