The author mentioned CtrlP for fuzzy filename matching. Its great because it's in pure Vimscript, but in my experience it becomes unusably slow for moderately sized projects. A month or two ago, I switched back to CommandT (requires Vim to be compiled with Ruby support, engine written in C) and haven't thought twice about it since then.
It's fine with many files, the only issue is when it indexes, which can't easily be automated. I just checked and it gets through about 2000 files a second on my MBP.
I've been meaning to try out matcher[0] for usage with CtrlP, I'm not sure how well it works but it's written in C and is purported to speed up search. Not sure if it's still being maintained, however...
It works quite well. The only negative I've found is that using matcher seems to disable CtrlP's usual highlighting of which letters in a search result are matched.
There's not much to maintain. I ported the matcher from Command-T out of its ruby-C wrapper, and it more or less just works. I use it dozens or hundreds of times a day.
I've found that my impression of CtrlP's speed varies dramatically depending on the project that I'm working on. For projects such as Bochs [0] (~750 files in CtrlP), I get annoyed at the initial .5-sec wait [1], but after that it's extremely fast. I don't have a particularly fast processor, either.
I find CtrlP breaks down with large projects such as the Linux kernel. While it's fast to find the initial list of files (2 seconds or so) it's extremely slow to actually search through said list, about .5-sec per keystroke.
[0] I'm not a maintainer, I just happen to be using its wonderful instrumentation hooks in a research project.
[1] It's about half a second on my laptop, which has an SSD. This time is dramatically larger if you have a rotary drive, more like 10-20 seconds IIRC.
I use CommandT primarily on my main machine but I also have CtrlP installed and they are both mapped to the same key (<leader>f) in a conditional. If I'm on a machine that has Vim compiled with Ruby, I get CommandT, otherwise CtrlP. Best of both worlds.