I'm trying to fill the area below a graph with 1024 points at almost 40 FPS. the CPU usage is way over what I had Expected it to be. I have read the notes about improving performance and saw this part:
Avoid complex fills, e.g. channel fills between graphs with thousands of points. This is especially relevant with the default software renderer, less so with OpenGL acceleration.
my situation does use channel fill just because i couldn't change axis-zero-value to something other than 0 (-150 in my case).
What am I doing wrong here?
Is there anyway I could improve the performance?

I'll be more than happy to share my code if that would be of any help.