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You could set the environment variable G4_NO_VERBOSE in the hopes of improving performance, though to date those improvements have not fully materialized, in fact as of G4 version 8.0.p01, a code modification (G4ParticleDefinition.cc) is required to prevent the setting of G4_NO_VERBOSE from skipping important code in G4. Tracy has patched this and it is included in our 8.0.p01-gl4 version of G4, located in $GLAST_EXT/srcExtLibs/geant4.8.
We also set G4_STORE_TRAJECTORY
0.01-gl4-src.tar.gz
Make Make sure to install the header files into a single common directory.
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