Please test my patch

the patch attached is not so different from the original soft-shadow help patch. My computer gets really sloppy with just a few boxes, on a friends computer it get all the way up to 200…
My specs is Lenovo T61 Duo 2Ghz 2Gb nvidia quadro nvs 140m
Maybe it s not top notch but i have never experienced slow downs for just a few elements on the render, is this shader so gpu intensive?

boxes.rar (238.1 kB)

333 boxes ~20 fps
444 boxes ~15 fps

nvidia 9800 M GS 1 Giga DDR3 Videoram

but from other patches i can tell you: this shader is for sure GPU-intensive

mmm that s the same as my friend got, i understand my card is not at the same level, by 8 boxes and go under 20 seems a bit too low…
Is there any other shadowing fx that will create shadow on objects onto each other?