Use precompiled header files to build your project faster. This is important if you are using ATL, MFC, or the Platform SDK header files.
Do not use /YX to increase compiler throughput. /YX tries to build a .pch file that fits your set of include files. If your include files are ordered differently in various source files, or if your source files do not include the same files, then the compiler rebuilds the .pch file. If you have different include-file patterns, those differences can slow down your build. /Yc and /Yu explicitly include the same header files in all source files and results in the same .pch file every time you build.
For more information on precompiled headers, see Creating Precompiled Header Files.