This mod tries to find a good balance between improving framerate, stuttering, and in-game visuals. While there are a few mods out there that accomplish some of these things, I was never 100% happy with them (to no fault of the authors of these other mods) and found myself tinkering with the DefaultEngine.ini properties. This is my current configuration, combining properties from several sources and tweaking them to better suit what I'm looking for. Changes include:

• Use better quality upscaling and anti-aliasing.
• Set max anisotropy to 16x.
• Disable depth of field and motion blur.
• Enable Subsurface Scattering (SSS).
• Increase number of corpses to 99 and set their lifetime to 9999 seconds.
• Various shader and texture optimisations and tweaks.
  

Certain tweaks are better for performance, while others offer better visuals. There are still trade-offs and compromises, but after about 12 hours of testing with these settings, I'm happier with the results. With everything set to Epic quality, 3440x1440 resolution, and VSync off, I went from averaging roughly 50 FPS in-game to around 80 FPS with occasional dips into the 70s on my GTX 970. Cutscenes and Photo Mode also have a decent boost in performance, going from the high-20s and low-30s to high-40s and low-50s. There is still stuttering every now and then as things load in, but the severity is lessened. I'm still not 100% happy with the compromises, but I will keep tweaking as time permits.

To install, copy pakchunk99-CustomEngine_P.pak to the "Jedi Fallen Order\SwGame\Content\Paks" directory where the game is installed.
Note: this mod is not compatible with any other mod that edits the DefaultEngine.ini file!

Credits
mrtaxerman's "Performance boost for Low End PC's and Steam Deck - Enable TAA Upsampling" and the SWFO_Custom_Ini_Kit mentioned in this comment.
deltron171's "Epic-Cinematic UE4 Graphics enhanced in Engine rendering Production quality NOT a Reshade"
Szaby59's "Faster Startup and Config Tweaks"
AlexPo21's "No Corpse Removal"