Performance issues using gdk_draw_rgb_image

["David J. Singer" <doc deadvirgins org uk>]

I'm writing an application under Linux that generates realtime audio and uses
GTK as the GUI.  I've been using "gdk_draw_rgb_image" to update the interface
components onto a backing pixmap, then copy the whole lot to a drawing area
at regular intervals.  The graphics stored in memory are all 24bpp, loaded 
from PNG files.

All has been well until recently I changed my X session from 16bpp to 24bpp 
and now the whole application seems to be struggling; there are noticable 
breakups in the audio.  

Is there a real performance issue with gdk_draw_rgb_image?  Is there a faster
way to do it?  And why does changing from 16bpp to 24bpp screw everything
up so much...?

As an aside, I've noticed there are also problems when I swap down to 8bpp 
mode I have problems displaying the colours correctly.  I thought this might 
be a dithering issue, but I've tried GDK_RGB_DITHER_MAX and 
GDK_RGB_DITHER_NONE and both seem to have the same effect.

Any ideas would be welcomed!

Regards,

-- 
David J. Singer
doc deadvirgins org uk
"Time flies like an arrow, fruit flies like a banana"