Storing JSON strings to the browser’s localStorage allows you to show data quicker on page loads, both for desktop and mobile applications. Using localStorage allows you to even create simple apps without any server (no syncing or collaboration, like a TODO app could do).
But like anyone, you want to pre-optimize for the massive amounts of data you’re sure you will be storing to localStorage. You don’t want your users to run out of room. So you grab an easy compression algorithm and use the worker API so your UI doesn’t freeze up and you’re ready to go!
There is a storage vs performance tradeoff. But who needs that in today’s world of… oh yeah, mobile, nvmd.
You can see what this might look like here: