Kingmakers performance
Nobody outside the playtests can measure it yet. What exists is the developers’ own account: performance was one of the two reasons the game was delayed, the goal is a true 60 frames per second on mid-range PCs without frame generation, and the game director has answered players about stutter, older hardware and stability on the Steam forum.

The target, in three numbers
The letter that called off the Early Access date put performance next to content polish as the reason: the studio wanted the game on “true 60fps to midrange PCs, without the need for fake frames”. The whole letter is on why Kingmakers was delayed, and the listed hardware is on Kingmakers system requirements.
Stutter
When a player worried that Unreal Engine 4 games are known for stutter, the director pointed to a system the studio built:
“We have our own system that we built to handle PSO caching in addition to the built in unreal 4 one. That is likely the stutter you’re talking about.”
The reply says the studio built its own PSO caching system on top of the one that comes with Unreal Engine 4, and that this is likely the stutter the player meant. It does not say the problem is solved. The one hands-on report found so far, from a convention floor, does not discuss stutter.
Who works on it, and how stable the last test was
“We have dedicated people that only work on performance optimization. It is their entire job. This is something we care a lot about and are constantly working on.”
“In terms of bugs the most recent playtest was very stable. I personally designed the multiplayer framework and it is made to be extremely robust. It can handle significantly more lag than most games and maintain stability.”
Both are the developer’s own assessment of its own build. The second matters for co-op, where four players share a battle over the internet; how that works is on Kingmakers co-op and multiplayer.
Older and low-end PCs
Asked what he meant by testers using a wide variety of hardware, the director described a spread rather than a floor:
“A large variety of amd/nvidia gpus and intel/amd cpus.”
In the same reply he said he did not remember the lowest spec they had tried, but had seen the game run on very weak machines at the lowest settings, and that the aim is for it to scale down as far as possible. There is still no official number below the Epic page’s minimum tier, which lists an RTX 2060. For a handheld, see Kingmakers on Steam Deck.
Still unanswered
Independent numbers will only exist once far more people are playing it. The first step toward that is the Steam playtest, explained on the Kingmakers playtest page.