Can anyone answer why core.preloadindex is false by default? Are there any pitfalls? I can't imagine a performance penalty.
Why is it not default - well, it was introduced in 2008, and they did it to improve performance on weak filesystems like NFS, and... Linus is of the opinion that it should be made default now - http://git.661346.n2.nabble.com/git-status-takes-30-seconds-on-Windows-7-Why-tp7580816p7580853.html
I wonder if preloadindex shouldn't be enabled by default.. It's a huge deal on NFS, and the only real downside is that it expects threading to work. It potentially slows things down a tiny bit for single-CPU cases with everything cached, but that isn't likely to be a relevant case.