title: Eclipse extreme slow at auto completion
body: <p>i have the following Problem: 
  I have a maven project and in these project eclipse is very slow. Sometimes it freeze for serveral seconds. And if want to use auto completion it takes up to one minute before this message is shown:</p>
  
  <blockquote>
    <p>The 'org.eclipse.jdt.ui.JavaAllCompletionProposalComputer' proposal computer from the 'org.eclipse.jdt.ui' plug-in did not complete normally. The extension took too long to return from the 'computeCompletionProposals()' operation.</p>
  </blockquote>
  
  <p>I can fix that issue by disable java proposals under content assist -> advanced. But then the auto completion wont work anymore. </p>