XRenderComposite with mask (A8) and with a src picture created by XRenderCreateSolidFill hits a slow path with Xorg-server-1.4.902.
If mask is ommited or a "normal" 1x1 RGB24 pixmap is used as src, the existing fast-path is used.
Its just a guess that this could be the result of exa_render.c/exaComposite ->
/* We currently don't support acceleration of gradients, or other pictures
* with a NULL pDrawable.
if (pExaScr->swappedOut ||
pSrc->pDrawable == NULL || (pMask != NULL && pMask->pDrawable == NULL))
I was using an intel-2.2.1 on 945GM.
I can't quite tell, but it looks like this is (was) really a problem with the -intel driver, and as it doesn't have XAA or EXA anymore I'm going to close as WONTFIX.