Thread by @emergetools

Last week we wrote how @peacock reduced app size & app launch after moving from RN to native

By beautiful chance, another streaming app did the same this week. Did the same effects occur? Well, yes, no & it depends

🧵 Breaking down HBO's new Max app

https://twitter.com/Baconbrix/status/1661058851054010392

So, HBO Max is now Max. New app, new bundle id, new logo, & entirely new codebase. Let's start by comparing the iOS size and architecture

iOS
HBO Max (old app): v53.20.1 - 60.4 MB install size
Max (new app): v1.0.1 - 108.8 MB

The new iOS app is 48.4 MB (~80%) bigger

Here's our X-Ray for the old HBO Max app. It consists of

~18 MB of images (top left)
~11 MB main.jsbundle (top right)
~15 MB main binary (bottom left)

The rest are misc frameworks, plugins, bundles, fonts, etc.

There are very few dynamic frameworks (3.9 MB) in the old HBO Max app - they're using Hermes for RN & some utility frameworks to help move around data

Now the new iOS app

There's 87 MB of dynamically linked frameworks, bigger than the entire old app

There are no plugins or extensions - a good opp. to statically link most of these frameworks. This will reduce app launch time and overall app size (explanation link at end)

Another thing that stands out is they have a 13 MB img in `error-overlay-bg`... this image is just a gradient (2nd screenshot)

So if we're comparing Peacock's switch to HBO's switch - Peacock switched & was able to remove libraries, HBO added them. There's a lot more going on and HBO could be doing a better job (static linking + our other insights), but that's one reason for increase in size

Now for Android

HBO Max (old): v53.20.1 - 54.9 MB download size
Max (new): v1.0.1 - 24.5 MB

The new app is 30.4 MB (~55%) smaller... so how is it almost double the size on iOS, but half the size on Android?

Here's our X-Ray for the old HBO Max app on Android

The main thing to notice is that HBO Max was shipping a universal APK, which means they are shipping assets, architectures, and languages for *all* devices / locales that they support vs. shipping what a specific user needs

The easiest place to see it is in the architecture portion of the X-Ray. You can see they're shipping the Hermes library 4 different times. This is happening for every library

Onto the new Android Max app

Max is shipping an AAB, meaning users download split APKs specific to their device

Before there was just one apk, now there is a base.apk + 3 others

That said, the change in size isn't solely b/c of split APKs

Native libraries decreased from 18.9 MB (old) -> 515 kb (new). But the old app still had ~5 MB of native libraries in each architecture, where the new app has 0.5 MB in one architecture

What are Native Libraries? Where Java & Kotlin compiles to dex, code written in C/C++ (among others) is packaged into native libraries (.so files) & compiles to native code

B/c there’s no more RN, the new app could remove most native libraries, which were used for RN

While native libraries decreased, the size from Dex increased, going from 3.6 MB -> 16.5 MB

This dex size increase is likely not directly related to HBO going native, rather a lack of optimization when building their release build (& potential security risk)

This is an entire post in and of itself, but tl;dr, the new app is not obfuscating any dex code. Code isn't minified and entirely human readable (this is a release build from the Play Store)

This requires more bytes to be shipped + loaded into memory when using the app

Recapping

HBO shipped an entirely new app (& logo), going cross-platform -> native

iOS nearly doubled and Android was cut in half (classic). The comparisons are not "apples to apples" though b/c of how much the apps differ

The decision to ship an entirely new app is massive - every single user is going to have to download the new app

Why a whole new app? How much of a reason was driven by wanting to go native asap vs. incrementally changing like Peacock did

Your guess is as good as ours

If you're interested, here's the thread on peacock

https://twitter.com/emergetools/status/1658885804276449309

& here's a good response thread from a RN dev

To be clear, we don't work w/ Peacock or HBO. We help both cross-platform and native teams monitor and improve their performance

On the side we like to tweet about interesting changes in apps

https://twitter.com/almouro/status/1659526815902228480

Post diving into static vs dynamic frameworks on iOS
emergetools.com/blog/posts/sta…

Here's a more in-depth explanation on split-apks
emergetools.com/glossary/split…

And the analysis pages

Max (iOS, new app)
emergetools.com/app/example/io…

Max (Android, new app)
emergetools.com/app/example/an…

HBO Max (iOS, old app)
emergetools.com/app/example/io…

HBO Max (Android, old app)
emergetools.com/app/example/an…