From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ramkumar Ramachandra <artagnon@gmail.com>
Subject: Re: [RFC/PATCH 0/7] Rework git core for native submodules
Date: Sun, 7 Apr 2013 23:52:02 +0530
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Ramkumar Ramachandra wrote:
> You can't control the most fundamental thing, stat(): this is the
> primary killer of performance on a large worktree.  There is currently
> no way to block stat(): new-style submodules offers a way to configure
> which submodules to block the stat() on.

Let me try to put this in simpler language.  When you run 'git status'
on your toplevel repository, old-style submodules runs git status on
each of the submodule repositories also: this is because submodules
were traditionally fixed; therefore, if you forget to commit some
changes in submodules before you make the superproject commit, you
might break the build.  In new-style submodules, you can prevent this
from happening on a link-specific basis.