Sometimes the smallest things make the biggest difference. That’s the lesson from Instagram, where they found changing the number of visible preview comments from 20 to just three had a significant increase in usage of the app.
Why? Because by focusing on the content people care about most (the photos and videos), and loading less of everything else, the app became more stable. So people stayed longer and did more.
Read the case study on the Instagram blog here. I like their takeaways:
- Question baked-in assumptions. In this case, we asked, “Why do we send 20 comments per media bundle?” Sometimes, questioning baked-in assumptions can lead to identifying low-hanging fruit.
- Measure. Before optimizing, take time to understand the potential impact. We saw how heavy comments were when we inspected the payload, and profiling led us to the realization that we could save CPU.
- Optimize for the most common case. A cardinal rule of optimization. Here, we consciously chose to optimize media loads rather than comment loads.
- Do the simple thing. “Do the simple thing first” is dogma at Instagram. After identifying the potential problem, we chose the simplest and most obvious course of action. And despite its simplicity, it yielded big results.
- Empathize. This is oft-repeated at Facebook. We use powerful phones on powerful networks, so this change was personally imperceptible. Yet it still impacted many people. Again, it’s worth noting that the observed improvements on Android outpaced those on iOS. This makes sense – Android phones tend to be cheaper and less powerful.
- Follow your nose. Here at Instagram NY, we’re chiefly responsible for ranking media (for instance, we personalize and rank media for “Explore Photos”). So a performance optimization like this wasn’t directly related to our work. But our intuition told us that this would be worth pursuing, and one of the best things about working at Instagram is that joining a specific team doesn’t constrain which parts of the code base we can touch. Within reason, we have the latitude to pursue anything we think is worthwhile.
