In some cases, and with some games, turning down "some" of the graphics settings actually is a very viable solution. It all depends on what aspect of the image you are adjusting. Even if your GPU has the horsepower to run this game on a CUSTOM setup with everything maxed to either ULTRA or whatever the highest settings are, that doesn't always equate to the optimum choices with some PC builds, Display model, resolution and sampling Freq.
FD has stated that they totally threw out the texture map database from 2.0 and replaced it with a totally different texture map system. That basically means that we are running a completely different game now than before, so it should come as no surprise that previous settings may no longer be ideal and performance is more likely to have changed considerably than remained the same as your 2.0 experience with your hardware.
All that said... I just finished some low altitude tests in the HIP 16607 system on several planets and I am not seeing any FPS issues on my Rig. But my rig is an overclocked monster performance wise, with very few games presenting it with any degree of difficulty FPS wise. But I always work on optimizing my settings rather than just cranking everything up to 11 and calling it a day! lol!
Do you have your FPS locked in at 60fps? Unless you are running a display that is truly 120hz or some value higher than the typical 60hz you are far better off locking in your FPS at 60fps since the game seems optimized to run at that rate.
There are also several new settings options in the Graphics section of 2.1. I would suggest doing some low altitude testing while trying various settings combos there. The "Materials WORK" setting is a big one with Horizons when it comes to smooth rendering of planetary surfaces/textures. Since we have different GPUs and a game with so many possible settings combinations, I don't think it would help much if I posted all my settings here. (I could if you think it would help though)
I would just do some playing around in there and see if you can find the right settings combination (s) that yields the smoothest FPS with your card and the rest of your rig. All I can tell you is that it should be totally possible to configure a solid and locked 60fps with your hardware. While many insist that they can perceive a difference, I hold to the notion that a locked 60 fps will look better overall than a slightly higher FPS that wanders all over the map, even though those rates are 60 and above.
Definitely try backing off the SHADOW QUALITY to Medium or lower, Reflections to LOW, but see if you can run your AA with SMAA and Supersampling at X1.5. Shadows and reflections don't need to be super high res. In fact, I think shadows look more realistic at Medium even though my Rig has no trouble running with that on ULTRA.
As I mentioned before, I am running a factory overclocked ASUS Strix GeForce GTX 980ti with the latest Nvidia driver, an Intel Skylake 6700k CPU overclocked to 4.7Ghz on Windows 10. The OS and Horizons are both installed and running on a 512GB Samsung 950 PRO M.2 NVMe SSD.
Some display settings of note:
My display is actually a SONY Bravia XBR W900 55" HDTV @ native 1920x1080 60Hz with the 980ti running DSR - 4.00x and DSR Smoothness at 100% via the Nvidia Control Panel's 3D settings - The interface is HDMI 2.0