The developers, Creative Assembly say they’re working on fixing it.
They plan to release the first hotfix this week.
To manage expectations, they do warn that this patch could be delayed if it’s not stable enough.

At first, you might expect to see small, targeted improvements to specific areas of the game.
This is a long-term projectone we expect to be a priority for the foreseeable future!"
In the meantime, some players have foundforcing the game into DX11 modecan help with those DX12 woes.

But yeah, an official fix would be better.
The whole situation is a bummer, especially when the game is good.
“It’s a genuinely epic construction; a proper Pillars-Of-The Earth-level feat of game development.”
Total War: Warhammer 3 is out now onSteamandEpicfor 50/60/$60, and on PC Game Pass too.
Disclosure: RPS co-founder Alec Meer (RPS in peace) wrote on Total Warhammer 3.