For those who play HD from time to time since SS classic is death - here are some useful commands which can help you to customize your game graphic, I've spend some free time and this is what I found as useful:
tex_fLODBias=10 (default value 0) makes all textures gray/blurry
sha_fShadowDarkness=0 (default value 1) reduce shadows
efx_iLensFlareQuality=0 (default value 3) flares off
ren_bFastLights=0 (default value 1) flare lights off
crm_bAllowRendering=0 (default value 1) remove grass
dcl_bAllowRendering=0 (default value 1) remove some wall details
tex_bNormalMaps=1 (default value 1) remove water effect
efx_bGaussianBlur=0 (default value 1) remove in water blurry effect
ren_bMirrorReflection=0 (default value 1) remove reflections
I have like 20fps more when i disabled some useless functions
If someone found something interesting and useful (besides graphic commands) share it and i will expand this list later.