title: Faster methods for set intersection
body: <p>I am facing a problem where for a number of words, I make a call to a HashMultimap (Guava) to retrieve a set of integers. The resulting sets have, say, 10, 200 and 600 items respectively. I need to compute the intersection of these three (or four, or five...) sets, and I need to repeat this whole process many times (I have many sets of words). However, what I am experiencing is that on average these set intersections take so long to compute (from 0 to 300 ms) that my program takes a very long time to complete if I look at hundreds of thousands of sets of words.</p>
  
  <p>Is there any substantially quicker method to achieve this, especially given I'm dealing with (sortable) integers?</p>
  
  <p>Thanks a lot!</p>