Oh yeah, I can see how the different filtering spots would make a difference.

Was just a bit surprised at the overhead of adding a command to the pipeline. A similar setup on linux would be like the following I guess (on a folder with 4600 files, 170 matching files).

    20ms time ls *.pdf
    35ms time find -maxdepth 1 -iname '*.pdf'
    60ms time ls | egrep '.pdf$'

I was more wondering if adding each additional command added so much overhead. Your numbers looks much more reasonable. Maybe the article I read had a big step due to filesystem / caching or something.