It's worth noting that bash is really a glue language to call other programs. If you mainly use the tools from the unix toolbox (i'm thinking of grep, for example) you really get the "scaling" (the performance) of native executable code.

Again, it really depends on how you handle your data.

Having a number of filters chained via pipes is really efficient, for example, when compared with looping over an array and executing some python/perl/ruby one-liners every time.