title: How to optimize linq query for speed?
body: <p>I have a linq query which fetches all records from the customer table to an observable collection as below:</p>
  
  <pre><code>customerList = new ObservableCollection&lt;customer&gt;(dbContext.customers);
  dgRecords1.ItemsSource = customerList;
  </code></pre>
  
  <p>the list is bound to a datagrid. 
  The customer table contains many fields nearly hundred. But I display only a few fields on the datagrid. My question is </p>
  
  <blockquote>
    <p>whether bringing of only selected fields from the database using linq query increase the speed the customer screen?  </p>
  </blockquote>
  
  <p>I need to filter and sometimes delete records from this list. </p>
  
  <p>Which is the best way to select few fields into observable collection, Can someone give some sample linq queries?</p>