first of all, your patch has a mxt extension, but it’s not a max text file, it’s a binary, so it should be mxb.

but i don’t think that was your problem.
i do notice a dramatic difference in playback from 4 to 5. it seems entirely caused by the smaller jit.cellblock on the left side of the patch.

perhaps it’s the rapidly changing dimension that is causing it to crap out in max 5.