React Native ListView slow to load
<p>I have a simple ListView which seems to take a long time to load its items. I've tested in Release mode, and its taking about 3 seconds to load the whole page. If I set <code>initialListSize={1}</code> I can see it building the list item by item.</p>

<p>The ListView JSX code:</p>

<pre><code>&lt;ListView
      dataSource={this.state.dataSource}
      renderRow={this.renderRow}
      renderSeparator={(sectionID, rowID) =&gt; &lt;View key={`${sectionID}-${rowID}`} style={styles.separator} /&gt;}
      style={styles.listView}
      initialListSize={1}
    /&gt;
</code></pre>

<p>And the renderRow method:</p>

<pre><code>  renderRow(row) {
    // console.log ('rendering scale row: ' + row.numerator + ':' + row.denominator );
    return (
      &lt;TouchableHighlight onPress={() =&gt; this.pressRow(row)} underlayColor="grey"&gt;
        &lt;View style={styles.rowContainer}&gt;
          &lt;Text style={styles.rowText}&gt;{row.hasOwnProperty('label') ? row.label : row.numerator + ':' + row.denominator}&lt;/Text&gt;
          &lt;Text style={styles.rowText}&gt;{row.hasOwnProperty('label') ? row.numerator + ':' + row.denominator : ''}&lt;/Text&gt;
        &lt;/View&gt;
      &lt;/TouchableHighlight&gt;
    );
  }
</code></pre>

<p>I'm not doing anything very complicated in renderRow... and the data had already been fetched in a previous view and passed in via <code>props</code>.</p>

<p>Is there something I don't know about that could be affecting load/render time? </p>

<p>This is iOS only and on an iPhone 4S. Only 12-21 rows in my tests.</p>

<p>I should also add that the core of the app is using the JUCE C++ framework and running some audio processing in one of the views. I have an audio processing thread that is only run when that view is visible - all other views (including the one with this ListView) will stop the audio processing thread. I've tried also stopping the audio thread in a similar manner but it did not make any difference. </p>