We here at Cult of Mac just can’t get enough of Instagram. It’s really hard to not love the little photo sharing app, even after it got bought by Facebook for $1 billion.

Have you ever wondered why images upload so quickly in Instagram? The whole app feels super snappy, and images can seem to upload instantly after you take a picture and apply a filter. What kind of magic is going on in the background?

As it turns out, the app’s design tricks you into believing its working faster than it really is.

Instagram co-founder Mike Krieger gave an interesting talk on his company’s hugely successful app at the “Warm Gun” design conference last December. The trick to Instagram’s snappiness is what Krieger called “moving bits in the background.” Essentially, actions are completed before the app’s design visually notifies the user.

With the case of uploading photos, Instagram sends the images to its servers before you expect it to. This visual illustration from Krieger’s presentation makes the point:

Data is sent as part of it is ready to go, and then the rest is matched up later. It’s not an ideal engineering solution, but it makes things happen lightning fast. The three takeaways from Krieger’s presentation about design philosophies in Instagram are:

Perform actions optimistically. Adaptively pre-load content. Move bits when no-one’s watching.

What we see is our photo instantly upload right when we tap the “Done” button, but Instagram is actually working in the background to get that photo up from the moment we take it. That’s smart design.

[via The Next Web]