When you first start up Baldur's Gate 3, you will be asked whether you want to use Vulkan or DirectX 11 as your API. An API is an application programming interface. This means that it allows different applications to communicate with one another. It also works to communicate with your operating system, ensuring you have a great connection.
You may be wondering which one you should pick then, Vulkan or DirectX 11. Thankfully, the answer is more simple than you may originally think. Considering it is a pretty long game, you will certainly want the best API. If you're stuck on which one to choose, read on to figure out which one works best for your computer.
Updated by Erin Rice on August 8, 2023: This update includes some new information released by Larian Studios regarding which API players should be using during their playthrough of the full launch game.
How To Change Your API
The Vulkan API was the default API for the game during Early Access; however, now DirectX 11 is the default. It doesn't matter what graphics card or anything that you have, DirectX 11is the default option. The only way to change this is to manually select Vulkan in the launcher window for the game. There is a small icon below the play button (see picture above) that will allow you to change this. All you need to do is click on whichever you want to use. This must be done before launching the game. If you do not, you won't have the option to change until you completely exit the game and relaunch the launch window.
Vulkan
Vulkan, as mentioned above, was changed from the default API. This API can be useful. Vulkan has been proven to have better performance than DirectX 11; however, this vastly depends on your computer's components. Vulkan is newer and is used in newer games, but DirectX 11 is still a classic many players prefer. If you have trouble while using this, switch back to DirectX 11. Considering even the Xbox Series S cannot handle the game, don't worry too much if your PC needs to use DirectX 11. You can select this API if you want to see better performance.
DirectX 11
DirectX 11 is the only other option for an API and it is also the default. Meaning, if Vulkan doesn't work for you, you will want to try out DirectX 11. Chances are, this will allow you to have more stability in your gameplay. Once again, changing from DirectX 11 is only recommended if you think your PC can handle Vulkan. While DirectX 11 is more stable, Vulkan offers much better performance and runs perfectly fine on many computers. At the end of the day, the decision depends on how your PC runs either API. You won't miss out on too much by selecting the more stable DirectX 11.