Source: http://forums.steampowered.com/forum....php?t=1034100

Kaizen's Left 4 Dead 2 config

I also recommend reading the rest of the thread regarding comments as they may be useful. I understand a lot of people crash with L4D2 after extended gameplay (lets say 3+ hours). If anyone manages to stablize their experience with changes to their config, please let everyone know!


Quote Originally Posted by FPSGOD View Post
Introduction

Just letting you know that I just released my L4D 2 config. This Left 4 Dead 2 performance config is designed to boost your frame rates (FPS) while maintaining the best possible graphics experience.

It also attempts to improve hit registration (i.e. the accuracy of your shots) by optimizing network settings, improve the visibility of the crosshair, and increase brightness so you can see enemies better.

Unfortunately, as was the case with the original L4D, L4D2 restricts most of the Source Engine’s console commands. Many of the best performance options can only accessed via the in game menu’s. Feel free to tweak any of the settings in this config to your liking, descriptions of what commands do are provided.

Download

Kaizen's Left 4 Dead 2 cfg version 1.1 - Last updated Nov. 21, 2009

INSTALLATION INSTRUCTIONS
Place this file (autoexec.cfg) into your Left 4 Dead 2 CFG folder,
similar to the path below:

<install folder>\Steam\SteamApps\common\left 4 dead 2\left4dead2\cfg\

REMOVAL INSTRUCTIONS
Simply delete (autoexec.cfg) and (config.cfg) found inside this folder:

<install folder>\Steam\SteamApps\common\left 4 dead 2\left4dead2\cfg\

STEAM LAUNCH OPTIONS
For an additional performance boost, customize your command line
launch options for Left 4 Dead 2 in Steam before starting the game

Setting Launch Options
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1. Go to "My Games" in Steam
2. Right click "Left 4 Dead 2" and select "Properties"
3. Select "Set launch options..." and enter the following:

-w 1680 -console -refresh 120 -heapsize 1572864 -high -noforcemaccel -noforcemparms -noipx -nojoy


Customizing Launch Options
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-w 1680 Sets resolution to 1680x1050; for 16:10 widescreen monitors - tweak as necessary
-console Enables developer console; so you can press ~ to enter commands
-novid Disables the intro movie, speeds up game on start-up (doesn't seem to work in L4D2 yet though)
-refresh 120 Forces 120hz/120fps refresh rate on monitor (if available)
-heapsize 1572864 Allocates RAM for the game; see table below for calculating optimal values
-high Forces high CPU priority
-noforcemaccel Forces desktop mouse acceleration settings
-noforcemparms Forces desktop mouse button configuration
-noipx Disables IPX network detection, local LAN (slight boot time improvement; you may need to remove this for LAN parties)
-nojoy Disables detection of 3rd party gamepads and controllers (slight boot time improvement)

Heapsize Setting
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Modify the heapsize command to allocate 50% of the RAM you have
in your computer (NOT video card memory!) in bytes.

Formula = RAM (in GB) * 1024 * 1024 / 2
1GB -heapsize 524288
2GB -heapsize 1048576
3GB+ -heapsize 1572864

Since L4D2 is a 32-bit application it is believed to be capped at
a maximum of 3GB of RAM. Setting heapsize to a value beyond this
may crash the game.

Additional Performance Links

- Left 4 Dead 2 Performance Tweaking Guide

- General Tweak Guides

See our Left 4 Dead 2 Achievement Unlock Guide as well.

Special Thanks Version 1.1

- To KeRupTion and mystrdat of the Steam forums for finding better
values of the network variables found in version 1.1

- To Fiszy, Kirisu, Jesse_lee, adsqew132 and anyone else I've missed
for their support and general interest in this config

- The entire Left 4 Dead 2 community

FPS Config for L4D1:

Kaizen's L4D1 config.

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END