As of today’s Nightly, Asyncrhonous Plugin Initialization is available for testing. It is deactivated by default, so in order to try it out you will need to navigate to about:config and toggle the dom.ipc.plugins.asyncInit preference to true.

If you experience any problems, please file a bug that blocks bug 1116806.

Happy New Year!

http://dblohm7.ca/blog/2014/12/31/asynchronous-plugin-initialization-nightly/