We would expect your Narrative post to load faster then images hosted on your own server, here's why:
We create 5 different versions, at different compression levels, of each of image you upload. This ensures that from whichever platform your visitors are viewing your post, they'll get lightning fast load times.
Your images are cached across servers in 180 locations worldwide, ensuring that wherever your visitors are they will get the same great experience!
For more information about why we host your images read this article.