title: why CPU usage close to reach to 100% when i use SOLR query all document
body: <p>I have a application using SOLR to query 2 million+ document and sort by time. 
  Query URL param like this <code>/select?sort=p_review_date desc&amp;rows=10&amp;start=0&amp;q=*:*</code>, parameter start is variable value, every request increased 10.
  When i make performance stress testing, the SOLR server CPU usage close to reach to 100%.</p>
  
  <p>Question:
  1.What causes high CPU usage?
  2.Is there a way to make low CPU usage, such as cache or other configuration.</p>
  
  <p>This is a part section for query cache configuration in solrconfig.xml 
      1024
      </p>
  
  <pre><code>&lt;queryResultCache
      class="solr.LRUCache"
      size="40960"
      initialSize="10240"
      autowarmCount="512"/&gt;
  
  &lt;documentCache
      class="solr.FastLRUCache"
      size="40960"
      initialSize="10240"
      autowarmCount="0"/&gt;
  
  &lt;enableLazyFieldLoading&gt;true&lt;/enableLazyFieldLoading&gt;
  
  &lt;queryResultWindowSize&gt;10&lt;/queryResultWindowSize&gt;
  
  &lt;queryResultMaxDocsCached&gt;500&lt;/queryResultMaxDocsCached&gt;
  </code></pre>