title: ExtJs 4 Line chart performance
body: <p>I have a simple line chart in EXTJS4 with multiple series. The total count of points in lines is about ~5k. </p>
  
  <p>ExtJs 4 chart renders it, but pretty slowly so I'm looking for a way to decrease rendering time. 
  Y axis - numeric, X axis - time. 
  Flash chart from ExtJs3 renders the same data set much faster.</p>
  
  <p>Any ideas?</p>