Wow that was an easy fix! Thank you for spending the time to find it choroba. For anyone who does not know, these files are used to generate lovely images of subroutine calls. Installing graphviz gives you a bunch of binaries to generate different kinds of graphs like:

neato -Tpng /path/to/nytprof/PerlModule-pm.dot -o some.png
[download]

Layout engines include: dot, neato, fdp, sfdp, circo, twopi, osage, patchwork

> Have you ever seen them in older versions of Devel::NYTProf?

I do not recall ever seeing them, but only recently began to check :-)

The NYTProf graphs are intense but callGraph is more pretty and easier to grok: github.com/koknat/callGraph