Use the console commands recordnetdemo demo_name, recorddemo demo_name,  playnetdemo  demo_name, playdemo  demo_name and
  playdemo stop. Example:
Multiplayer (Smaller Demo Files)
recordnetdemo uc_vs_uc // starts demo recording
stopnetdemo // stops demo recording

playnetdemo uc_vs_uc // starts demo playing
stopnetdemo stop // stops demo playing 

Singleplayer
recorddemo UCLevel1Tips // starts demo recording
stoprecording // stops demo recording

Singleplayer Demo Recording Benchmark 
1) Load Quake 4 using the shortcut that enables the console
2) Open the console using the ' key below ESC or 
press CTRL+ALT+~ (US Keyboards) or CTRL+ALT+' (UK Keyboards)
3) Enter the command timedemo ??DemoName??  usecache
4) Wait until demo has finished and note your FPS


Multiplayer Demo Recording Benchmark 
1) Load Quake 4 using the shortcut that enables the console
2) Open the console using the ' key below ESC 
or press CTRL+ALT+~ (US Keyboards) or CTRL+ALT+' (UK Keyboards)
3) Enter the command playnettimedemo id_demo001
4) Wait until demo has finished and note your FPS

demo1
idio: 23.69 fps
dude 30.35 (10.4.6)
dude 34.31 (XP SP2)

autoexec.cfg
seta r_useSMP "1"
bind o "toggle r_lightDetailLevel 0 3 5 7 9;addChatLine 'LightDetailLevel';addChatLine $r_lightDetailLevel" 
bind o "seta r_lightDetailLevel 9"

seta image_downSizeLimit "16"
seta image_downSizeBumpLimit "16"
seta image_downSizeSpecularLimit "4"
seta image_downSize "1"
seta image_downSizeBump "1"
seta image_downSizeSpecular "1"

seta r_brightness 1.4


seta image_usePrecompressedTextures "1"
seta image_useCompression "1"
seta image_downSizeLimit "1024"
seta image_ignoreHighQuality "1"
seta image_downSizeBumpLimit "1024"
seta image_downSizeSpecularLimit "256"
seta image_downSizeBump "1"
seta image_downSizeSpecular "1"
seta image_downSize "1"
seta image_lodbias "0"
seta image_preload "1"
seta r_useCachedDynamicModels "1"
seta r_skipBump "1"
seta r_skipPostProcess "1"
seta r_skipSpecular "1"
seta r_skipNewAmbient "1"
seta r_multiSamples "0"
seta r_useFastSkinning "1"
seta r_shadows "0"
seta r_useOptimizedShadows "1"
seta r_useTurboShadow "1"
seta g_projectilelights "0"
seta g_skipParticles "0"
seta g_decals "0"
seta g_brassTime "0"
seta g_muzzleFlash "0"
seta g_doublevision "0"
seta g_showPlayerShadow "0"
seta g_skipItemShadowsMP "1"
seta g_skipPlayerShadowsMP "1"
seta image_anisotropy "0"
seta ui_showGun "0"
seta image_filter "GL_LINEAR_MIPMAP_NEAREST" 
seta s_maxSoundsPerShader "0"