Performance problems with transitions.

[Thomas Schüßler <vindolin gmail com>]

Hi,

I'm having performance problems animating actors that are positioned 
over other actors.

I was implementing an electronic program guide when I noticed heavy 
stuttering when showing a spinning busy image over the program grid.

I've setup a python demo program, you can press g to toggle the grid and 
r to toggle the rotating actor in the front.

On our platform (A10, MALI 400 - sunxi driver, EGL backend) the CPU 
usage goes to 60% when rotating an actor with a PropertyTransition over 
a grid of 10x10 actors (just plain clutter actors with a background color).

When run on my development notebook (i7, Intel HD4400, GLX) it uses 
about 4% CPU with the same settings, but when I increase the actor count 
in the background to ~40x40 actors, even that machine jumps to 20% CPU 
usage.

Is this because all the actors in the grid need to be repainted on every 
animation step?

Is there something I can do to speed things up?

The demo code can be found at: 
https://gist.github.com/vindolin/81abe782ae4cbc174039

The default cell size is 100 pixels but this can be overridden with:

    python rotate_over_actor.py 20

Thanks
Thomas