Different apps use different strategies to wait with initialization until the localization is ready. Most of those strategies work around the mozL10n.ready() bug described in bug 993188.
When the bug is fixed, we will have two methods available: mozL10n.ready and mozL10n.once, which should simplify the bootstrap process for most of the apps.
This is the tracking bug for improving those apps.
I suspect that this effort should have impact on memory usage. We replace a lot of lifelong-lasting-closures (and retain data structures for the whole app) with fire-and-remove closures.
I don't think we can easily measure the impact since we don't have solid memory tracking yet, and we switch it app by app, but it may be important for Gaia team to know about it.