Some general tips for SSS materials:
anything but uniform spectrum type for scattering coefficient spectrum will be heaps slower than uniform. However, the absorption coefficient spectrum can be RGB with no loss of speed tho. So I suggest you give colour to your scattering by messing with the absorption RGB.
Increased the scattering coefficient will result in a greater 'SSS effect', but will slow the rendering speed.
Increasing the absorption coefficient will speed the rendering ( i think),
and make the material look denser as well.
I suggest keeping the absorption coefficient values similar to the scattering coefficient values, *unless* you're going for a milky look, where there is very little absorption.
Using a glossy_transmitter material instead of a specular material on the surface may help in acheiving a more SSS look as well.
The IOR of your SSS medium should be something like 1.5 to be physically plausible.
