title: Mobx performance
body: <p>I read from different sources that mobx outperforms react renderer and are faster then redux. However if I made couple of tests it shows that adding new data to  mobx observables are pretty slow. In react-native environment every milliseconds counts and it's tricky to use solution where even looping over 200 elements and filling array takes more then 100ms
  As I really enjoy mobx I hope someone can take a look a test code and give me some hints -  what I'm doing wrong and how to improve performance.</p>
  
  <pre><code>import {observable, transaction,autorun} from 'mobx'; 
  class Runner {
  
  list = observable([]);
  
  run() {
  
  
      const start = new Date().getTime();
      transaction(() =&gt; {
          for (let i = 0; i &lt; 200; i++) {
              this.list.push({
                  id: observable(i),
                  one: observable('1'),
                  two: '2',
                  three: 3,
                  x: 'xxxxx',
                  y: 'yyyyy',
                  z: 'zzzzz',
                  z1: 'zzzzz',
                  z2: 'zzzzz',
                  z3: 'zzzzz',
                  z4: 'zzzzz',
  
              });
          }
      });
  
      console.log('Execution time: ' + (new Date().getTime() - start) + 'ms services ');
  }
  }
  const runner = new Runner();
  autorun(() =&gt; console.log(runner.list));
  runner.run();
  </code></pre>
  
  <p>On my laptop it's takes about 120ms to complete. Without observable-s it's takes less then 1ms</p>