javascript - Does Firebase cache the data?

Question

I read somewhere a claim that Firebase caches the data.

So I ran this test that reads a semi large volume of data (about 400KB).

Here is the relevant code.

firebase.initializeApp(config);

var counter = 0;

console.time('firebase answered in');
firebase.database().ref('texts').once('value',onData);

function onData(snapshot){
  console.timeEnd('firebase answered in');

  counter ++;
  if(counter > 20) return;

  setTimeout(function(){
    console.time('firebase answered in');
    firebase.database().ref('texts').once('value',onData);
  },2000);
}

As you can see, the first time it loads data it takes a while, and subsequent calls take much less time.

firebase answered in: 1279.422ms

firebase answered in: 236.378ms

firebase answered in: 228.595ms

firebase answered in: 202.700ms

firebase answered in: 208.371ms

firebase answered in: 214.807ms

etc

But, still, if the data is cached locally ~200ms (sometimes more) seems like a lot of time to access local data. Enough for the user to perceive a delay when rendering the UI.

So is Firebase caching the data? What is happening in those ~200ms?

Answer 1

Waitting for answers