How to enable Vulkan & Metal in X-Plane
X-Plane 11.50 (full release notes) introduces support for Vulkan rendering on Windows & Metal rendering on MacOS. These are languages that control the interaction between X-Plane and your graphics card (GPU). Typically enabling this new API will yield faster performance while flying in X-Plane. Here is a video on how to enable this option in X-Plane.
Unfortunately, not all graphics cards are compatible with Vulkan & Metal. You can find the specific card requirements for this here.
Some 3rd party add-ons are not yet prepared to run in Vulkan/Metal. If you would like to use these add-ons with X-Plane 11.50, you can disable Vulkan/Metal rendering in the Graphics options (as shown in the video above) and then restart the application. This option will be present for the entirety of X-Plane 11's life. If you're unsure about the status of your favorite add-on, the 3rd party developer of that add-on is the best source of information.