title: Least resource way to animate curve line at D3 library
body: <p>Does D3 has built-in method to animate drawing of curve line?<br>
  I need a lot of animation curves in my project. I have tried Jason Davies solution <a href="http://www.jasondavies.com/animated-bezier/" rel="nofollow"><strong>link to example</strong></a>, <a href="http://www.jasondavies.com/animated-bezier/animated-bezier.js" rel="nofollow"><strong>link to js file</strong></a>, and it's working fine, but even Chrome browser begins to lagging after 30+ animate curves at one time.<br>
  In my case each curve has own coordinates, so browser should process the path for all of them, I am understand this, but Jason's solution recalculates all the path at every iteration, as I understood that was done for ability to dinamically change path via gray dots.<br>
  I'm new to d3 library so I can not realize, is it possible to calculate all path once, and then simply animate curve drawing from 0% to 100% ? Or everything is even easier and there are 
  simple method for this?</p>