Using localtime(time) is fine, but note it's only 1-sec resolution (which is probably fine for your needs). If you ever need something better, use Time::HiRes

I would highly recommend Devel::Profile since it can tell you what subs/calls are the bottlenecks (you get this information from Devel::Cover as well), and that is probablly the most robust way to debug your issues.

Lastly, an obligatory reminder to review your queries and schema/indices to make sure they are all appropriate.