As a quick and dirty test I tried running both Command-T and Ctrl-P against a directory tree containing some 26,000 XML files. Command-T takes roughly 10-15 seconds to become responsive. Ctrl-P chokes and requires a Vim restart after invoking it against this directory.
Is there a reason that Ctrl-P, FuzzyFinder, and Command-T choke on large directories? On windows, I've used this piece of software called Everything Search that seems to index the entire filesystem (say around 30,000 files) in under 5 seconds. That's really impressive and I love using it for that.
But it makes me sad to use these vim extensions choking on directories of similar size. Maybe NTFS vs ext4 has something to do with it?
The main thing that attracted me to Ctrl-p was that it is written in pure vimscript. Command-T, however, requires your vim to be compiled with Ruby support.
In the projects I have worked on, Ctrl-P seems faster than Command-T, but it's matching results are far from a replacement for Command-T. Ctrl-P often will not find files even when I type out the full file name. Command-T's match results are great. Ctrl-P will also show results from hidden/ignored directories. When Ctrl-P is smarter about its match results, I will use it more frequently.
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.
Is also quite good.
It would cool to have a performance comparison