MapTiler is a multi-threaded program. The modern CPUs has multiple cores and support of Hyperthreading - which provides multiple logical CPUs per core. This way MapTiler can provide higher performance even on a dual-core computer.
The free version is limited to 1 CPU, MapTiler Start and Plus have a limit of 2 CPUs for rendering, which doubles the rendering speed.
For the Pro versions, according to the version it will use all the available CPUs. With such power, it is easily able to render extremely large datasets (e.g. continents or the whole world). The number of purchased CPUs is automatically detected and if the computer is capable of faster rendering, it is possible to purchase additional CPUs for higher rendering speed.