I just noticed that in my previous message I forgot about another very simple way to same some memory, which is to untick the option "Resize auxiliary layers" in the "Output" tab. Sorry.
About the idea of cutting the image in strips: it might be worth trying something like that, thanks; currently however it would not fit well in the implementation (i.e. it would still slow down everything a lot, due to a "trick" which I've used to make the algorithm faster).
Also, I must agree about the script-fu language ;)
