[cutler]

IO.foreach without a block returns an enumerator.

[cutler]

You may be right. This version:

    IO.foreach('logs1.txt') {|x| puts x if /\b\w{15}\b/.match? x }

... runs in 1.3 secs, ie. same time as Python. Still, I exepcted Ruby 3x3 to beat standard Python.