Also, keep in mind that you have to get _very_ big before this becomes an issue. If you're at Yahoo, Google, MSN - yes, language issues can become a performance design consideration.
If you're at merely a big site, like Ticketmaster, IMDb, or Livejournal, with good software design you can handle a lot of load with reasonable responsiveness. (All those three sites are written in perl, in fact. I've worked for one of them.)
If your page views per day on your project aren't peaking in the billions, you're probably better off optimizing for the language that your team is most competent in.
No you don't have to be _very_ big, not even big, for the language to become a design consideration. You just have to do more than ship a few strings back and forth between the browser and the database.
If you're at merely a big site, like Ticketmaster, IMDb, or Livejournal, with good software design you can handle a lot of load with reasonable responsiveness. (All those three sites are written in perl, in fact. I've worked for one of them.)
If your page views per day on your project aren't peaking in the billions, you're probably better off optimizing for the language that your team is most competent in.