Have you tried TIME::Elapse. It reports elapsed time on the order of microseconds, and as such may be able to help you. There is also a Time::Hires module as well on CPAN that exports a gettimeofday() function.
Comment on Re: Network Reliability Testing, problems with buffered sockets?
Yep, I should have included that in the snippet, I'm using Time::Hires exporting gettimeofday to time the chunks :) Time::Elapse looks promising though!