Bartosz Kosiorek (@gang65) commented about dlls/gdiplus/image.c:
/* If any pixel has a non-zero alpha, ignore hbmMask */ src = (DWORD*)lockeddata.Scan0;
for (x=0; x<width && !has_alpha; x++)
for (y=0; y<height && !has_alpha; y++)
for (y=0; y<height && !has_alpha; y++)
for (x=0; x<width && !has_alpha; x++)
It desn't give performance improvement, but I would like to align it with the rest of the code.