You are going to want 8 cores running at at least @4GHz+ imo

Depends on what you mean by fine. I am pretty sure the CPU will be fine for 30fps, for 60 I am not sure. Maybe, maybe not. I have 2500K and am curious myself, if I cannot get 60 I will finally upgrade to coffee lake.

I'd be happy with a solid 30FPS cap, which I use for example on Witcher 3 as it otherwise goes from 60 to 28.

I've already got the game pre-ordered here at GoG, so it's perhaps a little late me wondering about performance, but anyway...

My PC is basically this:

Intel i7 2600 CPU - 3.40 Ghz
6gb RAM
6gb NVIDIA GeForce GTX 1060
Win7 Pro 64 bit

This runs Witcher 3 smoothly and with mostly high settings in all the graphic options. Same with GTA V and other reasonably graphics intensive games over the last few years.

I'm hoping Kingdom Come will run smoothly enough with that, because I'd rather not make my next PC "investment" for another year or so.

Although I'm always tempted to get a new rig built (incorporating my existing graphics card), it's still a cost I'd like to avoid at the moment, if possible, as the €800 to €1,000 spend I've estimated for the build I'd want is a hefty wedge of cash.

The branch of CryEngine this game uses uses one core at full tilt and one core anywhere from 20%-80% depending on the other's load. Additionally it is capable of offloading AI to a 3rd or 4th core if available, but this will almost never happen.

TL;DR - 2 cores is minimum and maximum for a CryEngine game, unless it's Star Citizen (which isn't really CryEngine anymore anyway, but Lumberyard + proprietary code)

I am however curious about that 6GB minimum, seems like pure optimism. Probably with everything at minimum or performance mode, AKA. unenjoyable

AMD FX 8370, 16gb RAM, AMD RX 580 8GB RAM.

Playing on 2K resolution with settings on High, except Shaders and shadows.
Average fps is around 40-45.

Crowded city like Rattay fps goes from 20 to 40.
Outside (villages. forest.etc) even 50+.

Seems that game still needs some optimlization, but runs much better than Beta client.

I tested the steamversion of a friend with my system:

Win7 64 Bit Professional (all Updates)
i5-6600k with 4,2GHz OC
3GB Sapphire Radeon R9 280X Vapor-X Tri-X Aktiv (Driver 18.2.2)
16GB G.Skill RipJaws 4 blau DDR4-3000 DIMM CL15 Dual Kit (with XML RAM profile)
525GB Crucial MX300

I start the game with this parameter (for 16GB)
-heapsize 2097152

I play the game on 1080p with settings on "high", only textures on "very high" and shadows on "middle" and have alway 40-45 fps. the fps minimum is 30fps and the maximum is 60fps (vsync).

I played the steam version on my budget PC: i3 6100, 1050 Ti 4GB, 8GB RAM, game on SSD. There are Low, Medium, High, Very high and Ultra presets. My PC can handle high alright, but sometimes dips below 30 fps. Toning down a few less important things like physics helps a lot.
But there is one fatal flaw that breaks my computer: when you see people popping in, which happens rather often in bigger towns, the game loads up lots of clothes and it likely has to decide which layers to be shown. As you can test it in the inventory view it takes some time and it is pretty much dynamic (kettle hat under the hood modifies the geometry to fit, though it is glitchy), so it has to be done all time a new npc appears. I would say this makes this game rather CPU intensive because of this single feature. Not sure if they can patch this.

As Cry engine is using extensively one core, you could try to overclock in bios just that one core (check in task manager which core it is). If overclocking has negligible effect on performance, then CPU is not the bottleneck.

I have my suspicions what could be the cause performance drops in populated areas (at least on ultra settings). In prologue the are two horses near a house when you have to collect the debt. Over the horse on the right the are many flies flying. When I look to left, everything is fine, but looking on the horse on right (of course standing near them) performance is taking a hit. That could indicate unoptimized texture size. Same was (and still is, since Bethesda haven't fixed it) with HD DLC for Fallout4. All textures, even for small objects, used constant, very high resolution. A button using same size texture as a shirt is not a good thing. Any one could check that?

In general (on my computer) KDC runs worse at 1080p than Witcher3 at 4K, while not looking better. The textures are looking to sharp (as if someone used unsharpen mask) on distant buildings (ca. 100m away), background seen through beard during dialogs in not blurred, etc.
A lot of room for improvements though :)

Hmmm....the steam version runs smoother than the gog version. Now I have freezes every 20 seconds for 1-2 seconds...and I had a bug now....my friends do not talk to me after throwing things on the house of the german....now I am sad why this version is so uggly.
Now I wait since 5 minutes at thr save synchronisation.......that is shit.

The game is running pretty smoothly for me on the following rig:

Win10
16GB RAM
X5687 CPU (Like i7-960) @ 3.6GHz
nVidia GTX970
Samsung 850 SSD

I am using the "-heapsize 2097152" startup tweak.

I have a relatively old machine and can run the game with most settings on low and textures in medium, with around 40 FPS.

My rig:
i3 4150 @3.5GHz
16GB RAM
Gigabyte Z97X
GTX 760 2GB - 1080p monitor
HDD
Win10

I am using the "-heapsize 2097152" startup tweak.

So, if you're not concerned about amazing graphics and can get by with ok ones you can play the game a little better than at console 30FPS with a low-end machine.