title: SQL query too slow in python pandasql
body: <p>I have create a query with pandasql in the following code :</p>
  
  <pre><code>csv_path = "C:/..."
  data = read_csv(csv_path, sep=';', encoding='utf-8') 
  
  q= """
  SELECT Address
  FROM data
  WHERE Id == 4357;
  """
  
  print pandasql.sqldf(q,locals())
  </code></pre>
  
  <p>So I create a <code>dataframe</code> from <code>.csv</code> file and then I make this query</p>
  
  <p>My original <code>.csv</code> file is 440k + rows long, while coding I am working on a 50 rows long file and even with that file it takes 1  minute for make the query and it use approximately 1.9 Go of the physical memory</p>
  
  <p>So I don't understand why it takes that much time and memory. I looked on some websites but there is not that much infos about pandasql out there</p>