As someone who likes adventure games and being a "turtle" player in general, a hack'n slash / tower defense game was just what the doctor ordered for me, and I've probably been spending way too much time with the game already.

I am also a completionist, so seeing the few "undiscovered" species in the log is simply unacceptable, so I have been delaying ending it as much as I can, trying to find what's left. Though I probably screwed myself when I removed a couple of the resource scouting outposts without checking every little nook and cranny.

I did use a resource cheat in the beginning, until I got the hang of all the mechanics, because I found the loading tool-tips to be of more use than the seriously lacking ingame instructions on how to connect things, and what to do about it when random icons started popping up on various buildings.

However, something unexpected, and also something I fear inherently cannot be fixed, is how the main base map is progressively slowing down over time. It's like everything is moving in slow motion right now, with consistently low FPS. It's not a hardware problem, I know that for a fact, and the issue is only present in the main map. And zooming out or when the base is attacked by creatures, it gets way worse. But if I jump to a resource deposit, everything runs silky smooth, regardless of what I do.

Game version is 1.45.
EDIT: Updated to 1.50 - little to no performance change with lots of cultivators on the map.

Hardware specs:
Windows 10 Pro 21H2
Asus Z490 Maximus XII Hero
Intel i9 10900K @ 5,00 GHz all-core (game temps in the mid-70s)
Aorus Xtreme RTX 3080 (driver version 496.76)
Corsair 64 GB 3200 MHz RAM
OS and Games on separate, dedicated NVMe SSDs (Adata XPG SX8200 Pro).

Playing on 1440p (2560x1440) max settings, though stretching it out across all 3 monitors (7680x1440) or half resolution drawing on a single screen, windowed mode or full screen, makes almost no difference.

I keep reading The Riftbreaker is mainly CPU-driven, which probably means most game objects (like trees) are CPU-drawn, like NPCs in Cyberpunk (hence the generally lower framerates in populated areas in CP77). I'm not a programmer, but my guess is this cannot be fixed, and that all the game objects are physically limited to take up 2-4 CPU-cores (unless object drawing, or whatever the issue is, can be scaled to use more CPU-cores depending on the system).

While I play, I see a lot of activity on 4 cores (and they're not even maxed out), while the rest of the cores are usually taking a snooze. The GPU seems to be almost idling most of the time as well. Almost ironically, the Cultivators, which are essential late game, are the worst FPS-killers.

In any case, this is highly annoying and effectively makes a rather compelling argument to finish the game as quickly as possible in future playthroughs to avoid the issue. The whole game also seemingly hard-locks for a few seconds while it auto saves, which was very surprising to see considering my game storage drives.

The solution to this problem, or should I rather call it a workaround, is to not build Cultivators at all on the main base map.

Regardless of graphics settings, even the half-resolution setting, the drawing of all Cultivator plants causes the system to slow down. I suspect the plants are CPU-drawn to not use a ton of GPU RAM / VRAM - which it does anyway; my RTX 3080 is struggling with this over time. 10 GB VRAM is not really enough with lots of Cultivators.

So a top tip is to use one of the outposts to place Cultivators. Like, fully saturate the that whole map with plants and resource buildings of all kinds. Solid storage, tower ammo factories, Cultivators and synthesizers (if needed). I used the Hazenite outposts - it's one of the first we get to, it is in the tropical zone (so lots of mud and sludge), and is a perfect place to fill with resource buildings of all kinds

That way it gives 0 performance impact on themain map, and gives the base map a lot more space to build the main buildings (Armouries, Laboratories etc.), defensive structures and power production / storage, without the need to protect or even consider the space requirements of Cultivators (like running pipes everywhere).

Cultivators on another map are also invulnerable and gives a permanent resource income for free for the rest of the game (after the initial hassle of setting it all up of course). Only need to revisit the map after unlocking the various material handling, as farming for example uranium, even with the Cultivators already set up with the plants beforehand, doesn't trigger the harvesting automatically.

Did you check 1.49 if it's any better?

I wasn't aware there was a newer version. Thank you, I'll update the game now.

Playing on version 1.50 now. Maybe it's a bit better. At least the sudden lag spikes when blowing up a bunch of plants isn't as bad now.

But the slow motion issue is still present.

EDIT:
No change with patch 1.50 - as the game goes on, and the Cultivators keep doing what they're supposed to, the game slows to a crawl. And with 0 FPS spikes when blowing up the plants.

UPDATE:
"Forcing" the issue with multiple boss minion attack waves through the dev console, here are some numbers from the MSI Afterburner / RivaTuner overlay:

GPU temp: 39°C / GPU usage: 0 %
VRAM: 7217 MB ( / 10000 MB)
CPU temp: 54°C / CPU usage: 15 %
RAM: 20135 MB ( / 64000 MB)
D3D12: 1 FPS / 1489,7 ms

Can someone please explain to me what the F*** is going on here!?
My guess is...this is a game for a RTX 3090, as this feels like a major VRAM issue!

...Well, this was surprising - the slow-down issue is a litteral feature according to the developers.
https://steamcommunity.com/app/780310/eventcomments/4534563767367322234/?ctp=2#c3182358518946687913

And this "feature" CANNOT be overridden. It's related to parallell CPU tasks, where I guess more cores would improve things, but if 10 cores and 20 threads is not enough (i9 10900K), what would be enough? This, the developers did not reply to.

So yeah, I have now refunded the game. Damn shame, because The Riftbreaker was pretty much everything I ever wanted in a game, but I will not play a game I know will slow down to a crawl over time every time.

Only options are to severely restrict the main base expansion (as the issue is related to the number of towers or cultivators on a map), or just rush through the whole game as quickly as possible.

So right now I will buy the game again when this issue is fixed. Or when seriosuly discounted, whichever comes first.

The solution could be a not simulate a work of these bots [i see them as white on map].
Something like adding 1 item per 10 seconds, no matter if this is visible or not.
Of course there need be math to check how many floors is usable ground and do that.

I think removing bots from map and the calculations rather than visibility scraping could give more fps.

Anyway, game is amazing, no crash even on MASSIVE attacks and turrets and AI.
Good job Developers!

It seems they have finally fixed the slow-down issue.
https://steamcommunity.com/app/780310/eventcomments/3382788361518746676/

With the latest patch, 1.32127 (GoG version), they have changed how the object drawing is handled. Prior to this, as a base expanded, there would eventually be too many objects on the map for the CPU to draw and keep track of, leading to a slow-down / FPS drop over time.

Now objects are handled differently, and it seems objects not visible in the camera view are not drawn at all.

Zooming out rapidly, objects fade in and are drawn as new ones as the camera view expands. But they no longer persist, and are removed again when moving away from that area of the map.

Possibly an unintentional benefit of this is that plants are drawn again as new ones - and can be scanned again. This is crucial for the rare ones, which sometimes would otherwise spawn only once or twice (that I have found on prior playthroughs).

I am not technically at late-game on my current playthrough yet, so it's too early to say for certain, but I have hopes for the issue being fixed permanently.