Reading your comment, I thought I would mention this especially nasty bug in 4.7.1: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54075 http://gcc.gnu.org/bugzill

Reading your comment, I thought I would mention this especially nasty bug in 4.7.1: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54075 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54075 Short description: a measured 3x performance regression from 4.6.2 to 4.7.1 when using std::unordered_map Not sure what the status is now, my Ubuntu and Debian boxes all report gcc 4.7.2.