http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53990
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-18 12:40:42 UTC --- It's maybe a little confusing for beginners, until they learn how it works, but it makes certain operations up to three times faster so it's a huge benefit. All good quality compilers will perform the optimisation, but if you don't want G++ to do it (and want your programs to be slower) you can use -fno-elide-constructors
