I'm running this with ImageMagick and would like to speed it up slightly by switching to GraphicsMagick if possible. In this, case I'm blending 30% of image1.png and 70% of image2.png together into result.png.
composite -blend 70 -geometry +0+22.86 image1.png image2.png result.png
I think you have to go with dissolve in GraphicsMagick but I'm not too sure how to go about achieving the same affect.