However you want to look at this data it equates to being able to handle a lot more requests on the same server. To change from CGI to CGI::Simple is a one line change as the interface is identical.... Is it worthwhile considering? For me yes, for you who knows?
I think it is very much worth considering, if you (like me) usually use only the methods also in CGI::Simple. It can mean that your site is put to better use, more happy users due to speed-up, and in theory can save costs due to not needing to upgrade. Well, no I don't really believe that to be true on account on just this change, but who knows? This, together with other optimizations can very well amount to this.
I also believe in doing things faster and better when it is worth it. Changing just one line in each script (a job for perl?) and gain that sounds very good to me. And I just can't see how it would hurt (unless your module is broken, of course).
Or maybe it is just my old days as a C=64 hacker that keeps on liking any optimization that can be done. Those were the days... :) Although I still withstand that some of the same thinking is good, and needful, for succesful web programming. Anyone who has visited (or failed to) a bogged down site should agree.