Tips: Performance

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Making a twenty-plus year-old game look like a modern one while still having good performance can be tricky. Thankfully, OpenMW offers many different settings options for managing performance in various ways.

This page will discuss specific strategies for gaining those precious FPS.

Table Of Contents

How To Test Performance

It's good to establish a testing pattern that you can repeat in order to quickly change and test settings values. Something like this:

  1. Pick a busy scene to test against (Balmora and Ebonheart both have spots that are very demanding).
  2. Edit your settings as desired.
  3. Create a file in the root of your base mods folder, and call it openmw-test.txt. Put this inside:
    tgm
    tcl
    player->setspeed 400  ; Or a higher value as desired
    • This will enable godmode, disable clipping, and set your player speed to something high so you can fly around very quickly when the game loads.
  4. Run OpenMW-Launcher.
  5. Under the "Advanced" tab, click "Testing".
  6. Check the box next to "Skip menu and generate default character", and enter the cell of your choosing in the box below that.
  7. Where it says "Run script after startup:", click the button labeled "Browse..." next to the input box and select the openmw-test.txt file you created before.
  8. Click "Play" in the launcher, and the game will load with your chosen scene.
  9. Repeat this process as you try different values.

After a bit of testing it's possible to arrive at settings that run well for your system, it just takes some patience.

Async Physics

Set async num threads under the [Physics] section from 0 to 1.

Advanced tip: If you know you've got multi-threading built into your bullet (this may require compiling it yourself), then you can go ahead and set that to the number of CPU cores you have, divided by two. This isn't a hard rule, but it is a decent starting point.

Field Of View

Personally, I love using a wide FOV in games that allow it. But I've found the performance cost can be significant, and actually nowadays just play with the default FOV.

If you've got a widened FOV, and want to get more performance out of your setup, then do try using the default FOV.

Groundcover

On this website, I suggest somewhat conservative values for groundcover settings but it may be possible to push that a bit further. For example: I've noticed that rendering distance = 12288.0 doesn't have too much of an impact on most scenes, and the pop-in is greatly reduced.

On a powerful machine, you can try to set density and min chunk size to 1.0 for more dense groundcover.

Mods

There are several modding projects that are dedicated to improving the performance of the vanilla Morrowind assets. These include Morrowind Optimization Patch and Project Atlas. These can especially help on lower-end systems.

Object Paging

OpenMW's object paging system is very powerful, highly configurable, and very well-documented. It gives you fine-grained control over how much distant stuff you see in-game. In order to maximize performance with it, you need to find the right amount of distant objects your system can handle.

The most powerful option for controlling this is object paging min size, which sets the size of things that will get paged (and thus, rendered in the distance). On my system with a powerful GPU, I set this to 0.025, but you could raise it higher for more serious gains (at the cost of more pop-in, and less distant objects overall).

Shadows

I've had the most success with maximum shadow map distance for getting performance out of shadows. I play with 4096, which is half the default value. It's worth tweaking this one for potential gains.

Viewing Distance

The viewing distance setting will have a major impact on your performance (combined with object paging).

I've found that a value of 71680, or just under 10 cells, is about as far I can go without having major drops in the busier scenes. If you have a less powerful GPU, experiment with 7 cells or lower, and a higher value for object paging min size.

Water

Last but not least, water settings can have a huge impact on performance without it being very obvious. Some things that can affect performance:

Performance Data

A collection of benchmarks I've done, with visuals provided by Flightless Mango and the excellent mangohud software.

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