gistfile1.txt

 ~ $ mksh /dev/fd/3 3<<EOF
\${BASH_VERSION+shopt -s expand_aliases}
alias slow-ass-loop='for x in $(printf '%s ' {1..1000000}); do :; done'
foo1() { for x in {1..1000000}; do :; done; }
foo2() { slow-ass-loop; }
unalias -a
time foo1; time foo2
EOF

    0m0.01s real     0m0.01s user     0m0.00s system
    0m0.45s real     0m0.45s user     0m0.00s system

 ~ $ ksh /dev/fd/3 3<<EOF
\${BASH_VERSION+shopt -s expand_aliases}
alias slow-ass-loop='for x in $(printf '%s ' {1..1000000}); do :; done'
foo1() { for x in {1..1000000}; do :; done; }
foo2() { slow-ass-loop; }
unalias -a
time foo1; time foo2
EOF


real    0m0.56s
user    0m0.50s
sys     0m0.05s

real    0m0.15s
user    0m0.15s
sys     0m0.00s

 ~ $ bash /dev/fd/3 3<<EOF
\${BASH_VERSION+shopt -s expand_aliases}
alias slow-ass-loop='for x in $(printf '%s ' {1..1000000}); do :; done'
foo1() { for x in {1..1000000}; do :; done; }
foo2() { slow-ass-loop; }
unalias -a
time foo1; time foo2
EOF


real    0m1.267s
user    0m1.252s
sys     0m0.015s

...got tired of waiting for bash after 5 minutes