Here's my take on Darkplaces settings for slow computers. Hopefully this will help some people with the fps lag. Keep in mind that this will make look like glquake if not uglier 
You can put these in your config.cfg file just after the bindings, your cl_color and cl_name.

You can put these in your config.cfg file just after the bindings, your cl_color and cl_name.
Code:
bgmvolume "1.000000"; cl_beams_instantaimhack "0"; cl_beams_polygons "0"; cl_particles_blood "0"; cl_particles_blood_alpha "0.500000"; cl_particles_blood_bloodhack "0"; cl_particles_quake "1"; cl_particles_quality "0.5"; cl_sidespeed "200"; cl_stainmaps "0"; cl_stainmaps_clearonload "0"; cl_upspeed "200"; gl_flashblend "1"; r_explosionclip "0"; r_hdr_scenebrightness "2"; r_lerpmodels "0"; r_lerpsprites "0"; r_lightningbeam_thickness "8"; r_shadow_realtime_dlight "0"; r_shadow_realtime_dlight_shadows "0"; r_shadow_realtime_world_dlightshadows "0"; r_shadow_realtime_world_shadows "0"; r_skyscroll2 "2.000000"; r_wateralpha "0.4"; sbar_alpha_bg "1"; scr_screenshot_gammaboost "1.500000"; scr_screenshot_jpeg_quality "1"; showfps "1"; v_brightness "0.000000"; v_gamma "1.500000"; vid_bitsperpixel "16"; vid_fullscreen "0";