XML from what I know and have heard, is basically not that great performance wise, I high doubt it outperforms ini files, or atleast wouldn't if ini file handler was improved (as the basic fact is, an INI file is simpler then an XML file, atleast as far as I know).

But people shouldn't be using it for it's performance, but for it's ease of structure.

If you want performance, XML isn't the way to go, nor is INI.