We have a real-space convolution code that we noticed was running notably slower in our c++ version than it was in our f90 version. So, we extracted out the key part of the code and started seeing if we could find a bottleneck. Removing multi_array_ref and using painful pointer arithmetic seems to show that the multi_array_ref's are the bottleneck: bmb24 reconstruct > g++ -v Reading specs from /usr/lib/gcc/x86_64-pc-linux-gnu/3.4.4/specs Configured with: /var/tmp/portage/gcc-3.4.4/work/gcc-3.4.4/configure --enable-version-specific-runtime-libs --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/3.4.4 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.4/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/3.4.4 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/3.4.4/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/3.4.4/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.4/include/g++-v3 --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec --enable-nls --without-included-gettext --with-system-zlib --disable-checking --disable-werror --disable-libunwind-exceptions --enable-multilib --disable-libgcj --enable-languages=c,c++,f77 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu Thread model: posix gcc version 3.4.4 (Gentoo 3.4.4, ssp-3.4.4-1.0, pie-8.7.8) bmb24 reconstruct > g++ -O3 arraysimple.cpp bmb24 reconstruct > time a.out 1.33693e+07 6.85547e+09 real9m40.203s users9m8.390s system0m1.889s bmb24 reconstruct > g++ -O3 arraynoboost.cpp bmb24 reconstruct > time a.out 1.33693e+07 6.85547e+09 real9m401m13.103s users9m81m10.551s system0m10m0.343s Boost version: boost-1.32.0 Can anybody confirm these results, or suggest a fix? Thanks, Grant Goodyear -- Grant Goodyear web: http://www.grantgoodyear.org e-mail: grant@grantgoodyear.org