The developer of X-Plane, Laminar Research has been working hard to deliver major upgrades to integrate the Vulkan Application Programming Interface.
Laminar Research has taken to their Facebook page to show two comparable graphs that detail the performance differences in terms of FPS that the new Vulkan system will bring to X-Plane.
OpenGL in simple terms is a way of rendering 2D and 3D graphics on your PC which communicates with your GPU to enable hardware-accelerated rendering. Typically, OpenGL is considered old technology which dates back to the 1980s. Obviously, it has seen some upgrades but developers, including Laminar Research, are moving over to newer APIs such as Vulkan and Metal.