Vulkan is a new graphics API that provides high-efficiency, low-level access to modern GPUs in a wide variety of devices from PCs to smartphones. APIs like Vulkan and DirectX 12 make better use of multi-core CPUs to streamline code execution and eliminate software bottlenecks, particularly for draw calls.
Games typically make thousands of draw calls per frame, but each one creates performance-limiting overhead for the CPU. Vulkan and DirectX 12 reduce that overhead, which means more objects, textures and effects can be drawn to the screen.
The 3DMark API Overhead feature test measures API performance by making a steadily increasing number of draw calls. The result of the test is the number of draw calls per second achieved by each API before the frame rate drops below 30 FPS.
The purpose of the test is to compare the relative performance of different APIs on a single system. The API Overhead feature test is not a general-purpose GPU benchmark, and it should not be used to compare graphics cards from different vendors. For more details, please read the 3DMark Technical Guide.
The API Overhead feature test is available now in 3DMark Advanced and Professional Editions. Standalone versions will prompt you to download and install the update. On Steam, 3DMark updates automatically. The API Overhead feature test is not available in 3DMark Basic Edition or the Steam demo. Note also that the Vulkan test replaces the Mantle test found in previous versions.