CMakeLists.txt that is being generated just invokes UBT, just like other projects. The ultimate way to build the engine is to run mono UnrealBuildTool.exe UE4Editor Linux Development, all project files (including Visual Studio) boil down to that.
As for the compilation speed, it heavily depends on the hardware and not the build system. On a workstation-class machine (16+ cores, 32+GB RAM) it should take less than half an hour to compile from scratch. (See here for benchmarks: https://docs.unrealengine.com/en-us/GettingStarted/RecommendedSpecifications/HardwareBenchmarks)