There have been a variety of UnixShells for a long time (see QuarterCenturyOfUnix).
During that long time, computers have increased in speed perhaps a millionfold. What was once way too slow is now done in the blink of an eye.
There are two major command interpreter code forks in Unix: the BourneShell and the CeeShell. Here's an example that will email all your files to someone else:
BourneShell: /bin/sh, ksh, bash, and others
for i in *
mail -s $i $address <$i