How many milliseconds does it take to parse YAML, XML, or any other file format for which a parser written in C is widely available?
> the user is expected to do all configuration through the graphical interface.
Changing configurations using the GUI is exactly what Unity and GNOME 3 don't allow the user to do. Try changing anything other than the desktop background.
YAML and XML may be slower than this, but Python 2.6's built-in 'json' module averages less than 20 milliseconds to parse a simple 1000-element "object"/dict on my system.
This isn't even the highest-performance JSON parser for Python, and parsing into less dynamic C or C++ datastructures would probably be somewhat faster still.
Either way, the principle stands. If a desktop environment wanted to standardize on JSON + C/C++-style comments, they could extend their standard parser easily enough without meaningful performance impact.
[1] http://stackoverflow.com/questions/244777/can-i-comment-a-js...