I have a crappy laptop, yet i must play dark souls (I MUST). Normally when you try lowering the internal resolution below 720p in DSFix, the game crashes. So here's how to lower resolution (and another trick) to anything you want - without crashing - for a higher and more stable fps.

NOTE: if any of the terms i use are confusing, please leave a comment and i'll make changes to the guide to make it more readable.

DSFix is needed for lowering the internal resolution.
If you don't use / don't know about DSFix, here's a link:
http://blog.metaclassofnil.com/?tag=dsfix

The download contains a README for how to use it. I'm assuming you know about it from here on.

Before you make the changes listed in the following sections, run dark souls with DSFix at default settings. Don't worry if the game is abysmally slow, since this is to test whether the game crashes with DSFix's default settings. If it's not crashing, continue on. If it is, find out why and fix the issue before applying the below settings.

Turn off all beauty options (AA, SSAO, etc.) in DSFix for further increases in FPS if you haven't already.

These lines in DSFix are used to change internal resolution for the game:

# internal rendering resolution of the game
# higher values will decrease performance
renderWidth 1920
renderHeight 1080

# The display width/height
# 0 means use the same resolution as renderWidth/Height
# (use for downscaling - if in doubt, leave at 0)
presentWidth 0
presentHeight 0

Internal rendering resolution controls the crispness of the game world, and display width/height changes the crispness of the game UI (HUD, menus, enemy health bars, damage display numbers, etc.). For some reason, dark souls doesn't like low UI resolution, and this causes the game to crash on the starting menu.

To get around this, put display width/height to a moderate value. I use "presentWidth 1280" and "presentHeight 800" and have no problems with it. Now the UI stays crisp no matter the internal resolution of the game world, and dark souls stays happy.

You can now set the internal resolution to whatever you like without crashing.

Here are screenshots of some different resolutions:

840 x 484:

640 x 400:

400 x 200:

20 x 10 (impractical, but showing how far you can go):

So for me, lowering the resolution even to something as low as 400 x 200 still gave me performance problems in areas i know i shouldn't have. My game would stutter almost every second, and i'd usually be at 15 FPS when i should be at 30. You may be experiencing the same thing.

So to reclaim the lost frames, smooth out performance, and get rid of stutters, unlock the framerate in DSFix. After doing so, it should work oh-so-smoothly. There may still be slow downs in graphic-heavy areas such as Blighttown and Demon Ruins, so you may want to lower internal resolution further in those areas if it's a bother.

Now, with the framerate unlocked, there may be some odd behavior when your framerate is higher than 30. For example, you may notice bloodstains play way too fast, or you don't travel as far when you roll off an edge. If you don't want to experience the wonkiness of framerates higher than 30 FPS, put "FPSlimit 30" for the default 30 FPS cap.

Now with the resolution lowered and the optional step of unlocking the FPS, you're once again prepared to die, but now at smoother framerates.

Using DSFix:

- Set the display width and height to a moderate value. I use "presentWidth 1280" and "presentHeight 800".
- Set the internal resolution to whatever you like.

If the framerate is still choppy/slow, again in DSFix:

- Unlock the FPS.
- (Optional) Set the FPS limit to 30 to avoid the wonkiness of framerates higher than 30 FPS.

Praise the slightly-pixelated sun!