Matlab MEX slowdown without code change

Question

I have been developing a bit of code for the last few weeks. The Code is wrapped within a MEX file in MATLAB. Until yesterday my usual test took about 1 second. Suddenly after recompiling the code without changing anything, the same code takes more than 4 seconds.

The only changes happened in a function totally unrelated to the function I am calling. It seems as all compiler optimization has vanished from one second to the other.

Maybe one of you experienced similar happenings in the past and knows how to deal with that?

Thank you for your suggestions.

Edit 1:

As I assume it is something compiler dependent, here the output of the compilation command (using verbose mode)

----------------------------------------------------------------
->    MATLAB                = /Applications/MATLAB_R2010b.app
->    CC                    = gcc-4.0
->    CC flags:
         CFLAGS             = -fno-common -no-cpp-precomp -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5  -fexceptions
         CDEBUGFLAGS        = -g
         COPTIMFLAGS        = -O2 -DNDEBUG
         CLIBS              = -L/Applications/MATLAB_R2010b.app/bin/maci64 -lmx -lmex -lmat -lstdc++
         arguments          =  -DMX_COMPAT_32
->    CXX                   = g++-4.0
->    CXX flags:
         CXXFLAGS           = -fno-common -no-cpp-precomp -fexceptions -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5
         CXXDEBUGFLAGS      = -g
         CXXOPTIMFLAGS      = -O2 -DNDEBUG
         CXXLIBS            = -L/Applications/MATLAB_R2010b.app/bin/maci64 -lmx -lmex -lmat -lstdc++
         arguments          =  -DMX_COMPAT_32
->    FC                    = gfortran
->    FC flags:
         FFLAGS             = -fexceptions -m64 -fbackslash
         FDEBUGFLAGS        = -g
         FOPTIMFLAGS        = -O
         FLIBS              = -L/Applications/MATLAB_R2010b.app/bin/maci64 -lmx -lmex -lmat -L -lgfortran -L -lgfortranbegin
         arguments          =  -DMX_COMPAT_32
->    LD                    = gcc-4.0
->    Link flags:
         LDFLAGS            = -Wl,-twolevel_namespace -undefined error -arch x86_64 -Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5 -bundle -Wl,-exported_symbols_list,/Applications/MATLAB_R2010b.app/extern/lib/maci64/mexFunction.map
         LDDEBUGFLAGS       = -g
         LDOPTIMFLAGS       = -O
         LDEXTENSION        = .mexmaci64
         arguments          =  /usr/lib/libarmadillo.dylib /usr/lib/liblapack.dylib /usr/lib/libblas.dylib
->    LDCXX                 = 
->    Link flags:
         LDCXXFLAGS         = 
         LDCXXDEBUGFLAGS    = 
         LDCXXOPTIMFLAGS    = 
         LDCXXEXTENSION     = 
         arguments          =  /usr/lib/libarmadillo.dylib /usr/lib/liblapack.dylib /usr/lib/libblas.dylib
----------------------------------------------------------------

-> g++-4.0 -c  -I/usr/include -I/Applications/MATLAB_R2010b.app/extern/include -I/Applications/MATLAB_R2010b.app/simulink/include -DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -fexceptions -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5  -DMX_COMPAT_32 -O2 -DNDEBUG  "file1.cpp"

-> g++-4.0 -c  -I/usr/include -I/Applications/MATLAB_R2010b.app/extern/include -I/Applications/MATLAB_R2010b.app/simulink/include -DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -fexceptions -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5  -DMX_COMPAT_32 -O2 -DNDEBUG  "file2.cpp"

-> g++-4.0 -c  -I/usr/include -I/Applications/MATLAB_R2010b.app/extern/include -I/Applications/MATLAB_R2010b.app/simulink/include -DMATLAB_MEX_FILE -fno-common -no-cpp-precomp -fexceptions -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5  -DMX_COMPAT_32 -O2 -DNDEBUG  "file3.cpp"

-> gcc-4.0 -O -Wl,-twolevel_namespace -undefined error -arch x86_64 -Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk -mmacosx-version-min=10.5 -bundle -Wl,-exported_symbols_list,/Applications/MATLAB_R2010b.app/extern/lib/maci64/mexFunction.map -o  "distanceSplinePoint.mexmaci64"  file1.o file2.o file3.o  /usr/lib/libarmadillo.dylib /usr/lib/liblapack.dylib /usr/lib/libblas.dylib -L/Applications/MATLAB_R2010b.app/bin/maci64 -lmx -lmex -lmat -lstdc++