Tackling library IO performance

[Benjamin Kosnik]

>I wanted to get some feedback before I crank out patches that people
>don't want, especially since the format cache had been removed once.
>Are there things I should be careful of or avoid doing in putting
>these patches together?

I think you've done a good job of explaining yourself. I'm interested in
seeing these patches as well. Please try to keep the formatting
consistent to C++STYLE formatting.

thanks,
benjamin