I just tried it on different sprites, it runs smooth and I see no performance drops, even on full layers (yes, I made silly tests too).
Thanks a lot for sharing this great effect! :)
It could be more useful if we could tweak the effect intensity. On most of my sprites, everything is full white and very few parts of the image are readable, even if the original sprites were medium/dark.
Could it be added easily, or is it a lot of work?
Anyway, thanks again for sharing, I'm never tired of trying cool new effects like this one :)