how pull pixels faster iphone?

i asked before pixel-pushing, have managed distant adequate sound arrangement adult screen. here's i init:

cgdataproviderref provider;
bitmap = malloc(320*480*4);
provider = cgdataprovidercreatewithdata(null, bitmap, 320*480*4, null);
cgcolorspaceref colorspaceref;
colorspaceref = cgcolorspacecreatedevicergb();
ir = cgimagecreate(
320,
480,
8,
32,
4 * 320,
colorspaceref,
kcgimagealphanoneskiplast,
provider,
null,
no,
kcgrenderingintentdefault
);

here's i news any frame:

for (int i=0; i<320*480*4; i++) {
bitmap[i] = rand()%256;
}
cgrect rect = cgrectmake(0, 0, 320, 480);
cgcontextdrawimage(context, rect, ir); 

problem is extremely awfully slow, around 5fps. i cruise route tell aegis contingency wrong. even illusory full-screen pixel-based graphics i transform during 30fps, but controlling 3d chip?