dx9, shadow settings:
mat_shadowstate "1"
r_shadowmaxrendered "11"
r_shadowrendertotexture "1"
r_shadows "1"
cl_blobbyshadows 0
2639 frames 18.362 seconds 143.72 fps ( 6.96 ms/f) 8.019 fps variability
cl_blobbyshadows 1
2639 frames 16.299 seconds 161.91 fps ( 6.18 ms/f) 9.278 fps variability
It definitely does something for anyone who has shadows enabled.