What kind of system ressources do you think about? RAM? Cpu usage? Runtime?

The first one might need less RAM because it doesn't seem to slurp the whole file into RAM as the second one does.

Finding out about runtime, I'd have to do some benchmarking, but I think, for small files the latter example might perform slightly better...

Best regards,
perl -e "print a|r,p|d=>b|p=>chr 3**2 .7=>t and t"