If you know shell scripting and do a significant amount of it, then it's definitely worth it to learn Perl :-)

Speaking about performance in general is always very difficult, but yes, Perl can often be faster than shell scripts, one of the reasons being that Perl has a lot of functionality built in that shell scripts only support by executing external processes.

Could you show us the bash script? Having a real test case to benchmark would really help.

Without knowing more, processing 1500 records in 18 seconds sounds slow. Is the script doing any kind of network activity that could be the bottleneck?