On Mac OSX 10.9,I am facing an issue with NSOpenPanel in My application. NSopenpanel takes longer time to launch it for the first time. I observed that [NSOpenPanel openPanel]
This is probably because of the special architecture of the NSOpenPanel. The open panel runs in it's own process called "Powerbox", especially if the app is sandboxed. The Powerbox does not have an API. Even if your app is not sandboxed, make sure you sign your app appropriately.
I'd love to point to some documentation about it, but the whole Powerbox and Sandbox are poorly documented and when introduced also poorly implemented.