Precompiled headers can speed up build times considerably. This article says 'up to one order of magnitude': http://gamesfromwithin.com/?p=39

Both GCC and Visual C++ support precompiled headers.

On the CMake mailinglist, a cmake macro for enabling procompiled headers was posted (http://article.gmane.org/gmane.comp.programming.tools.cmake.user/23266) -->

On Thu, Aug 6, 2009 at 2:34 PM, ML<mailinglists@...> wrote:

Hi All,

Can CMAKE use Pre-compiled headers now? I thought that I recalled their
being an issue at some point, not sure.

Can anyone shed some light?

I do this for my Visual Studio builds with a macro.

macro( LA_PCH_SUPPORT ProjectName )
if (MSVC)
if (USE_MSVC_PCH)

		set_source_files_properties(${ProjectName}PCH.cxx
			PROPERTIES
			COMPILE_FLAGS "/Yc${ProjectName}PCH.h"
			)
		foreach( src_file ${${ProjectName}_SRCS} )
			set_source_files_properties(
				${src_file}
				PROPERTIES
				COMPILE_FLAGS "/Yu${ProjectName}PCH.h"
				)
		endforeach( src_file ${${ProjectName}_SRCS} )
		
		list(APPEND ${ProjectName}_SRCS ${ProjectName}PCH.cxx)
		list(APPEND ${ProjectName}_EXT_HDRS ${ProjectName}PCH.h)

endif(USE_MSVC_PCH)
endif (MSVC)
endmacro (LA_PCH_SUPPORT)

Then its usage in a project named laGUI

SET( laGUI_SRCS
./src/laMultiViewFrameMgr.cxx
./src/VTK2dWidget.cpp
./src/laCentralWidget.cxx
./src/laImageSliceView.cxx
./src/laWLWidget.cxx
./src/laTableWidget.cxx
./src/laPipelineWidget.cxx
./src/ImageSliceViewer.cxx
./src/InteractorObserver.cxx
./src/laVTKInteractorStyleImage2D.cxx
./src/laVTKCommandImage2D.cxx
./src/la2DView.cxx
./src/la3DView.cxx
)

SET( laGUI_EXT_HDRS
./Include/InteractorObserver.h
./Include/laVTKInteractorStyleImage2D.h
./Include/laVTKCommandImage2D.h
)

SET( laGUI_MOC_HDRS
./Include/ImageSliceViewer.h
./Include/laMultiViewFrameMgr.h
./Include/VTK2dWidget.h
./Include/laCentralWidget.h
./Include/laImageSliceView.h
./Include/laWLWidget.h
./Include/laTableWidget.h
./Include/laPipelineWidget.h
./Include/la2DView.h
./Include/la3DView.h
)

#Add precompiled header support
LA_PCH_SUPPORT(laGUI)

Then externally create

laGUIPCH.cxx
laGUIPCH.h

in the same folder as the CMakeLists.txt file for the project.