I just overheard Wincent say that Command-T was always written in C because previous Ruby plugins that attempted to accomplish the same thing was too slow. Command-T was written to be instant.

FWIW I ran

    cd
    vim
    <Ctrl+P>
    (wait 10~15s for it to complete)
    <ESC>
    :q
    find . |wc -l
    183239

Fast enough for me. (MacBookPro5,5 + aftermarket Samsung 470 SSD)

Command-T is faster for sure. But it lacks critical features that Ctrl-P has (no vim -ruby dependency for one).

When you start vim again and hit ctrl+p, does it do all that over again?

If I don't quit vim, and do Ctrl+P, things got cached (which you force-refresh with F5) so it's instant.

If I quit and restart vim, the Ctrl-P cache is invalidated thus it's scanning again, but it's down to 3~5s since disk reads got cached by the OS.

Yes. But you can specify a local cache file if you want... in which case it would not start over when you restart.

Ah, I see. I added a similar feature to Command-T, because scanning one of my projects trees takes a couple seconds.