When I am in space I have full 75 FPS. But when I get on a planet it drops and stay stuck at 38 FPS.
Dunno why. Any ideas / same observation?

Are you running an NVidia card? If so, one thing that may help is to launch the GeForce Experience app and, under Settings | General, turn off In-Game Overlay. My system is a little underpowered but turning this option off changed it from occasionally hitting single-digit frame rates to just a mild hesitation now and then. Can't hurt (AFAIK) and might help.

I didn't install GeForce Experience. Don't need it. But thanks anyway. ;)

I think, generally speaking, planet surfaces are simply much more complex. The slowdown seems to be the result of all the extra geometry, textures, effects and AI calculations. I've visited a "dead" planet recently, with no feral creatures and very little vegetation, and the FPS seemed much more stable there.

In other words, when you're flying through space there's far less data for your computer to calculate, and that's why those sections tend to run more smoothly.

I'm also starting to think this game may be much more CPU dependent, unlike other games which rely more on the GPU. Would make sense, with all of the procedural generation, and the amount of creatures on some planets.

I'm getting the same issue, and it's pretty widely reported on Steam and Reddit as well. On my end it appears to be hitting the GPU much harder than the CPU (my ageing i7 3820 does not ever max out and actually NMS pretty well distributes the load across logical cores, but my gtx 970 is maxed out at 100%). I get an average of 40fps on planets, except when looking straight up or down (no planet stuff to render basically), whereas with pathfinder i was getting 70+ fps consistently on planets. Hopefully HG is looking into this, but so far there's been no indication either way.

Game engine causing this "issue" was in my thoughts too.

Anyway, the framerate is maybe strangely low on planets but at least stable. So still playable. Which is an upgrade compared to the firsts versions of the game on PC.

Perhaps it will be fixed in a way, or perhaps not. For example my brother is running on a 1070 and has 75 FPS both on planets and in space.
So... meh.

Sounds like you have v-sync engaged and because your setup cant hit 75 in certain areas its going to half the vsync rate of your monitor (i assume you are running at 75Hz with your monitor).

The game must be double buffered vsync so even though you may be able to hit 75 fps in certain areas the moment you drop even 1 frame below 75 the game will drop to a framerate divisible buy your monitor refresh.Try setting monitor to 60 hz and see if your framerate steadys.Or you could turn off vsync.....if you can live with the tearing that will introduce.

So I changed the monitor to 60 Hz but... it did the exact same thing. x) Framerate was also divided by 2 on planets.

For the moment, and depending what Hello Games does to optimize the grafics, it's fully normal to have huge FPS drops in these conditions:

- A lot of creatures spawning with buildings nearby, especially once you unlock all the rooms with Atlas v.2/v.3
- A lot of different flora close together and creatures
- Intense space battles with multiple ships and freighters

In these situations FPS may even drop below 20, and there is nothing you can do about, it's the game, not your system.

What generally helps is:
Video cards with 4GB+ VRAM should not have any trouble, or you really have to optimize your OS.
VSynch=OFF can help but doesn't with some cards
Have a 'clean' OS with the minimum programs installed on your computer
Have all tweaking and enhancing programs for your GPU disabled.