Here is a somewhat foolish test with a shell script, that forks "/bin/true" 10 million times.
C:\>busybox sh
~ $ echo 'x=10000000; while [ $x -gt 0 ]; do true; x=$((x-1)); done' > timetest
~ $ time sh timetest
real 0m 46.86s
user 0m 46.76s
sys 0m 0.04s
Here is the same test with Debian's dash shell, one of the fastest: $ cat timetest
x=10000000; while [ $x -gt 0 ]; do true; x=$((x-1)); done
$ time dash timetest
0m33.79s real 0m33.50s user 0m0.05s system
Not a great test, but there is quite a difference there.