title: ReactNative ScrollToIndex too slow
body: <p>im using react native to create an app for a legal document. i need the document to be scrollable. i rendered it using VirtualizedList.
  thing is when i try to use scrollToIndex(index: 'something') performance is too slow.
  my list contains about 4000 rendered items (each being about a paragraph long).</p>
  <p>is there any way to make this run smoother?</p>
  <pre><code>export default function App() {
    const scroller = useRef();
  
    return (
      &lt;SafeAreaView&gt;
        &lt;View style={styles.upperContainer}&gt;
            &lt;CustomButton
              onPress={() =&gt; {
                scroller.current.scrollToIndex({ index: 1547 });
              }}
            /&gt;
          &lt;/View&gt;
        &lt;View style={styles.flatContainer}&gt;
          &lt;VirtualizedList
            ref={scroller}
            data={data}
            renderItem={({ item }) =&gt; (
              &lt;CustomText data={item.content} type={item.type} /&gt;
            )}
            getItem={(data, index) =&gt; data[index]}
            getItemCount={(data) =&gt; data.length}
            keyExtractor={(item) =&gt; item.number.toString()}
            initialNumToRender={4000}
            onScrollToIndexFailed={() =&gt; {
              alert('error');
            }}
          /&gt;
        &lt;/View&gt;
      &lt;/SafeAreaView&gt;
    );
  }
  </code></pre>