title: Slow first query after update
body: <p>I have a 9Gb index and when I update the index (with delta-import or via xml), the first query is always very slow. </p>
  
  <p>I have FastLRUCache and a newSearcher query configured (it's launched according to the log), but still have slowness in the first query.</p>
  
  <p>How can I debug the source of this slowness?</p>