I asked about this in IRC and got a request to send some details to the
mailing list, so here they are -

Whenever I try to use tab completion with a git command, zsh hangs for a few
minutes using full cpu before coming back with an answer.  It usually isn't
causing much disk activity, just cpu.  The command I try to use most often
is "git checkout foo<tab>", where foo is the first few letters of a branch
name, but the slowness seems to also happen anywhere else I need to complete
a filename or branch/tag name.

Some details of my repository:
- 96,000 files
- .git is 17GB
- Deepest directory nesting in the repository is 15 levels but most files
are no deeper than 7 levels

I'm running zsh 4.3.10 with _git from today's CVS.  Host OS is Ubuntu
10.04.1, 6GB of RAM with an Intel Core2Quad 2.4ghz.  My git repo is on an
SSD (OSZ Vertex I think), so none of the hardware should be a bottleneck.
 Bash-completion on the same setup in the same repo works fine without any
delays.

-Brett