Mantle increases performance through greater efficiency and also offers ease of programming. The API uses AMD Catalyst drivers and a GCN-enabled GPU or an accelerated processing unit (APU) along with an application or game that is coded for Mantle.
Early 3D programs tended to need graphics card-specific APIs for best 3D performance. Direct3D and OpenGL both provide APIs that end that requirement but result in more overhead from translation and more complexity from supporting many devices. Mantle works more directly with the GPU to require less translation.
Because next generation consoles like the X-Box One and Playstation 4 games all use AMD’s GCN, titles developed for consoles require less coding to port to PC and they more fully support AMD GPU features.
NCIX benches and explains Mantle: