So who knew...
I'm currently working with extracting data from a system with an XML based command UI, so I am fairly often dumping serialised (using Data::Dump) perl objects out whilst debugging.
To make the piles of debug output easier for me to parse I pushed the files through Perl::Tidy.
You would not believe how long it takes, or how much memory is required, to run 110MB of perl datastructure dumps through perltidy!
Actually I don't know how long or how much memory it took either - I killed it after half an hour and 3GB.
I mean, who knew! :-)