Start Time Benchmark Shell Vs Python

Shell environment function is no cost. While python takes 100ms.

Shell script takes about half the time of python to startup.

mac> time strings.say_hi.py
Hi

real	0m0.088s
user	0m0.066s
sys	0m0.016s

mac> time ${SCRATCH_SHELL}
hi

real	0m0.051s
user	0m0.041s
sys	0m0.009s

mac> time strings.add_prefix hi hi
hihi

real	0m0.000s
user	0m0.000s
sys	0m0.000s