Performance Tweaks

This article relates to performance issues for players. For performance information for mappers, see Performance: Essential Must-Knows

Show FPS

First, you can check how many FPS are achieved by opening the console with Ctrl+Alt+~ (tilde, ^ on German keyboards) and type:

com_showFPS 1

Optimizing the performance

Stop running programs in the background

Programs running in the background might either eat up memory that is needed for Doom3, and thus cause swapping to the hard disk, or they might consume CPU time or other resources. This can cause either general slowdowns or hickups during game play.

Run Doom3 in fullscreen

Running Doom3 in windowed mode might be quite a bit slower than fullscreen mode.

Reduce your resolution!

On older cards, Doom3's render engine is very expensive for every per pixel drawn, and reducing the resolution will help the most. For instance, at 1600x1200 the game needs to draw four times as many pixels as when running 800x600. The result with 800x600 will not look as bad as one might think – but the frame rate improvements might make it much more playable.

If you cannot set the resolution you want in the settings menu then enter it in doomconfig.cfg.

To edit doomconfig.cfg:

Uninstall any current mission in the New Mission menu.
Close Dark Mod
Edit doomconfig.cfg in the darkmod folder
Re-install the mission.
Whenever you UNinstall and install another mission, these changes will migrate to those FMs as well.

(Alternatively, edit both the doomconfig in the darkmod folder AND the one in the current FM game folder, eg, doom3\chalice.)

Search down for these cvars first and replace them with the values shown:

seta r_mode "-1"
seta r_customHeight "640"
seta r_customWidth "480"

Configure Video RAM

Change: seta com_videoRam "128" to the appropriate value for your GPU

(Nvidia) Disable Index Buffers

Change: seta r_useIndexBuffers "1" to "0"

(Note: This tweak may not work with upcoming changes to The Dark Mod so revert it before upgrading)

Set the ambient shading to "Faster"

(Not valid for Thief's Den demo)

Inside the settings, change the ambient rendering method to "Faster".

Set the interaction.vfp to 'Standard'

(Not valid for Thief's Den demo.) In the video settings menu, change the interaction shader to Standard. Ambient lighting will not look as good, but you may gain a few frames per second.

The game is very slow!

If you get less than 10 FPS, or the game even stutters, please try this:

Look into your DoomConfig.cfg inside your saintlucia or thiefsden folder and check that the following settings are like shown below:

 seta image_usePrecompressedTextures "1"
 seta image_useNormalCompression "2"
 seta image_useAllFormats "1"
 seta image_useCompression "1"
 seta image_preload "1"

Image downsizing

As a last resort, you may enable image downsizing: at the console, set image_downSize to 1 and then set a limit with image_downSizeLimit, e.g., "image_downSizeLimit" "256". This reduces texture memory requirements and may completely alleviate hard drive thrashing. There are similar cvars for bump and specular maps as well. Note: This may result in very blurry briefing and menu screens.

Drop in Frame Rates when Viewing Water

Some players have reported a drastic drop in performance when an agitated water surface is in view. This on a Radeon card. Try entering this in the console. It disables the water visible surface effects but at least it might let you play normally...

set r_skipPostProcess "1"

Blurry Briefing and Menu Screens

If you get blurry briefing and menu screens then in DoomConfig.cfg make sure you do NOT have image_downSize 0. Instead set it to 1. But see also #Image downsizing

Lightgem interleaved calculation

By default lightgem calculation occurs every frame. You can set lightgem calculation to happen only once per several frames by setting tdm_lg_interleave console parameter to values higher than 1. For example, typing:

tdm_lg_interleave 3

in console tells TDM to recalculate lightgem value every third frame.

This tweak can increase average FPS, but it often produces noticeable stuttering, especially on slow machines.

Field of View Decrease

Note that this setting might occasionally produce odd effects such as a grabbed object seems to move a little on release.

You can get a performance improvement if you decrease the field of view. By default this is 90 degrees but you might try entering in the console or in your doomconfig.cfg...

g_fov 85

In addition, if you are playing a mission that is too good to miss and reach a very low performance area which is almost unplayable on your machine, you might consider setting the field of view extremely low temporarily to get you through then restore to 90 later...

g_fov 50

Note from Fidcal: I have played comfortably on g_fov 75 and even think perhaps it makes nearby objects more realistically close so you can get right up to a table, etc. Not noticed any problem with restricted view.

Player Shadow

The player shadow slightly reduces performance. It has no game effect at all (not seen by AI for instance) apart from atmospheric effect so if you want to disable it enter in the console:

g_showplayershadow 0

Or, in doomconfig (see above) change the following line from "1" to "0":

seta g_showplayershadow "0"

Player Lantern Shadow

You may notice a drop in performance while using the player lantern.

Add "noshadows" "1" to entitydef light_lantern_moving in tdm_playertools_lantern.def and this stops the player lantern casting shadows. This helps improve performance slightly when using the lantern.

Gameplay Performance Tips

If you have done everything else you can and performance is still poor then one or two things you might do in game to help:

Close all doors after you have passed through. Generally the game has to process both areas until you close the door if the doorway is still in sight.
Kill or KO every AI you can. You might not like to play that way but generally, AI still hog resources even out of sight (depending on how set up in the game.)
Avoid alerts. A dozen guards searching for you will really slow things down on a low-end machine.
Try to look down at the ground when moving along. Gazing up at a grand vista will slow you down. Best to do your gazing while standing still.

Last resort: Upgrade your hardware

Modern games need a lot of computing power, and while you don't need the absolutely newest hardware to play them, upgrading single components of your machine can help tremendously:

If you got less than 2 GByte main memory, consider upgrading your memory. This really helps to reduce swapping, which introduces quite noticeable slowdowns.
If you got a graphic card from NVidia older than the GF 7x00 series, consider upgrading it.

Upgrading your CPU will be quite complicated and the cost might be so sadly high that you could rather buy a new complete computer. Upgrading the hard disk will usually not help much with gaming, unless you are running out of free space.