FWIW on My Machine(tm) bash goes from ~4 times slower to ~70% slower on the simple startup test just by changing the locale: $ time for i in $(seq 1 1000);

FWIW on My Machine(tm) bash goes from ~4 times slower to ~70% slower on the simple startup test just by changing the locale: $ time for i in $(seq 1 1000); do bash -c ":" ; done real 0m4.475s user 0m3.234s sys 0m1.287s $ time for i in $(seq 1 1000); do dash -c ":" ; done real 0m1.067s user 0m0.408s sys 0m0.704s $ (export LC_ALL=C; time for i in $(seq 1 1000); do dash -c ":" ; done) real 0m1.043s user 0m0.409s sys 0m0.679s $ (export LC_ALL=C; time for i in $(seq 1 1000); do bash -c ":" ; done) real 0m1.721s user 0m0.783s sys 0m0.986s