perrin, as is usual with webapp questions, is right on the money. The web framework you use, if used properly, has almost zero impact on your ability to scale with the number of requests. The limiting factor, in almost all cases, is getting to the right data for the request.

What the web framework does is affect the ease of development and testing. The right framework can mean up to a 10x difference in development and maintenance speed. It can also mean the difference in the ease of testing. For example, testing is something that Catalyst and RoR have made a big priority in doing easily. This is unlike HTML::Mason or CGI::Application, for instance.

In terms of testing, the big thing is to make sure that you are at least testing at the request level. So, things like Test::HTML::Content are good things.