You could try and write your own imagecollide function. Once you load your images, create an array the same size as the image, only storing whether a pixel is masked or not. That way, you only need 1 bit per pixel, and checking should be fairly quick, just comparing two arrays. And it will never be the whole array either as it's very unlikely two big images will completely overlap.
Not great, but a possible workaround :o)
That aside, i've never had any problems like this with 2d work. Very odd i've never came across this myself...
Not great, but a possible workaround :o)
That aside, i've never had any problems like this with 2d work. Very odd i've never came across this myself...