title: SOLR MLT too slow
body: <p>I have a SOLR query using MoreLikeThis to get similar docs. But when trying to do some performance tests (using jmeter) and running 50 clients, it is incredibly slow (like 2-3 requests/second). It almost does not matter which type of instance is used (in AWS I tried m3.xlarge 4cpu,16GB as well as m3.2xlarge 8cpu/30GB). Does anybody see a potential problem or some hint for me?</p>
  
  <pre><code>/mlt?fl=*,score
  &amp;q=DocID:1234
  &amp;wt=json
  &amp;mlt=true
  &amp;mlt.fl=JobID Field1 Field2
  &amp;mlt.mintf=1
  &amp;q=*,score
  &amp;sort=score desc
  &amp;fq=!Field3:3
  &amp;rows=10
  &amp;fq=(!join from=Field1 to=Field1)DocID:1234
  &amp;fq=(!join from=Field2 to=Field2)DocID:1234
  </code></pre>
  
  <p>thank you very much</p>