Dans options de lancemet : tu copies colle tout ca :

-w 640 -h 480 -fullscreen -lv -soft -noaafonts -high -dxlevel 81 -heapsize 1572864 -single_core -noaafonts -wavonly -novid -noforcemaccel -noforcemparms -noipx -nojoy
Cree un autoexec.cfg que tu placeras dans le repertoire :
\Steam\SteamApps\common\left 4 dead 2\left4dead2\cfg
(tu crees un nouveau fichier .txt bloc-note et copie colle tout le entre
dedans , puis renomme le "autoexec.cfg":

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// GRAPHIC & AUDIO/CAPTION SETTINGS + BOOST FPS
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cl_detail_max_sway "0" // Amplitude of the detail prop sway (Default 5)
cl_forcepreload "0" // FORCES TO PRE-LOAD LEVEL (SMOOTH GAMING) (Default 0)
cl_viewmodelfovsurvivor "65" // VIEW MODEL OF SURVIVOR AND INFECTED (Default 51)
cl_ragdoll_limit "0" // Maximum number of ragdolls to show (-1 disables limit) (Default 20)
dsp_enhance_stereo "0" // ENHANCES THE STEREO EFFECT (Default 0)
dsp_slow_cpu 1 // REDUCES THE QUALITY OF DSP SOUND EFFECTS, IMPROVING PERFORMANCE ON SYSTEM WITH LOWER CPUs
//--TEST--//
adsp_debug "0" //
dsp_enhance_stereo "0" // Uses hardware sound
voice_scale "1" // Max mic boost
snd_musicvolume "0.5" // Sets the music volume to the maximum (Default: 1)
snd_pitchquality "1" //
//snd_updateaudiocache // Sound stuttering fix
//--TEST--//
mat_bloom_scalefactor_scalar "0" // Amount of bloom scaling
mat_grain_scale_override "0" // FILM GRAIN AMOUNT (Default 1)
mat_monitorgamma "2.6" // MONITOR GAMMA MAX BRIGHTNESS (Default 2)
mat_monitorgamma_tv_enabled "1" // MONITOR GAMMA ADDICIONAL BRIGHTNESS (Default 0)
mat_queue_priority 2 // TO USE IF YOU GOT LAGS/ LOW FPS (Default 1)
muzzleflash_light "1" // EMITS MUZZLE FLASH Def 1
func_break_max_pieces "0" // NUMBER OF DEBRIS YOU CAN SEE (DISABLED) (Default 15)
r_ambientfraction "0.2" // ??? (Default 0.2)
r_cheapwaterend "1" // worse water rendering
r_cheapwaterstart "1" // worse water rendering
r_drawmodelstatsoverlaymin "0.1" // (Default 0) time in milliseconds that a model must take to render before showing an overlay in r_drawmodelstatsoverlay 2
r_drawmodelstatsoverlaymax "1.5" // time in milliseconds beyond which a model overlay is fully red in r_drawmodelstatsoverlay 2 (Default 1)
r_dynamic "0" // show DYNAMIC SHADOW (DISABLED) (Default 1)
r_eyemove "0" // DISABLES REALISTIC EYEBALL MOVEMENT (Default 1)
r_eyesize "0" // (Default 0.24)
r_eyeshift_z "0" // (Default 0.22)
r_eyeshift_y "0" // (Default 0.4)
r_eyeshift_x "0" // (Default 0.2)
r_PhysPropStaticLighting "0" // Faster lighting on phys objects (Default 0)
r_radiosity "4" // ???
r_skyboxfogfactor "0.0" // Lerp between 2D skybox rendering and fog color. 0.0 means regular 2D skybox rendering, 1.0 is fully fog color.
