FPS Limit: Try this setting between 60 and 120. It depends on your pc.
Texture Details: This has a surprisingly low effect on performance, so feel free to leave it on the high side.
Model Details: Turning this down doesn’t grant as many extra frames as you might think, and there is the potential for long-range engagements in Deathloop, so I’d leave it up.
Shadow Details: Turn this down and benefit from the vastly improved FPS instead. Medium/High setting suggest.
Water Details: Affects surface reflections as well as the inclusion of extra visual pizzaz like seafoam. Leave this up if you can; not every mission takes you to the shores of Blackreef, so you won’t always appreciate the extra detail, but then that also means turning it down won’t always produce extra frames.
Terrain Details: This doesn’t do much to help the most frame-hungry, close-range gunfights, though, so again you can aim high.
Decal Details: Changing this from Ultra to Very Low did absolutely nothing, so go for maximum detail here.
Ambient Occlusion: You can’t turn this off, so most PCs will be best off with the FidelityFX CACAO Performance option. I suggest FidelityFX CACAO Balanced if your pc can handle it.
Sun Shadows: This defaults to “Simple,” which actually looks fine, though if you have a sufficiently muscular GPU it’s worth switching to the “Raytraced” setting for a more realistic look.
Post-Process Anti-Aliasing: Smooths out jagged edges. There are four quality levels, starting at Off and ending at Temporal; higher settings will yield smoother edges, albeit at a heavy performance cost. I suggest to use Temporal.
TXAA Sharpness: Only enabled if you select Temporal for Post-Process Anti-Aliasing, you can adjust the intensity of the smoothing-out effect from a scale of 1 to 20. Unsurprisingly, higher values have a more marked adverse effect on frame rate.
Sharpness Post Process: This applies a sharpening filter to partially counteract the blurriness that can come from applying anti-aliasing. There are two settings, Standard and FidelityFX CAS; there’s not much difference quality-wise, but I got an extra 2fps from the latter, so you might as well choose the same.
Camera Motion Blur - Bloom - Depth of Field - Lens Flare: I am not a huge of this effect. I put all of this to OFF.
This game is very poorly optimized, just like it was with Dishonored. These are just tips for trying to get a little extra but they won't fix basic engine problems. Probably Denuvo also takes away further performances, but it is all to be confirmed.