This has nothing to do with perl per se, but according to Jakob Neilson in Designing Web Usability, a response that's less than 0.1 second long is seen as instantaneous to the user. This would be ideal as there's no disruption to the user's navigation. A response time of one second is noticable to the user, but still, there is little disruption to them. A response time of ten seconds is very noticable to the user and disrupts navigation (i.e. it's seen as an actual pause), but it's still within the bounds of a person's ordinary patience. Anything more than ten seconds, Neilson says, and you risk frustrating the user. This is just a rough guideline.

Personally, I suspect Neilson (or the studies that Neilson quotes) are a bit pessimistic. I think by now people are pretty well trained to wait a bit longer for their web pages to show up.

So, to answer your question, if you can bring up your web page within about ten seconds (including the time it takes to travel across the network, on a server with average to moderately high load), then I think you're doing okay.

By the way, although Benchmark is good for optimising, you might want to look into Devel::DProf (or Apache::DProf if you're using mod_perl) which will help you track down where your code is spending its time.