If you have even had to build the Chromium browser from source using GNU Make, you will know that it is a very slow process even on a 4 core system. Ninja is a build system written by Evan Martin, who works for Google and is a Chrome developer, with the specific goal of improving the edit-compile cycle time. It currently only works on Linux. It can be dropped into a Chrome or Chromium build and behaves very similar to the GNU Make utility except it builds things much faster than make can. Typically you should use the Gold linker