title: Leaflet polyline performance issue
body: <p>I'm currently working with Leaflet 1.0.3 and here is my problem.
  I have a lot of GPS position which are displayed on my map.</p>
  
  <p>I have a <code>for</code> loop where I create a circle marker on each position :</p>
  
  <pre><code>var position = new L.latLng(lat, lng);
  coordinates.push(position);
  
  L.circle([lat, lng], 50, {
      color: 'red',
      fillColor: '#f03',
      fillOpacity: 0.5
      }).addTo(map).bindPopup(date.replace('T',' '));
  </code></pre>
  
  <p>With thousand of position, no performance problem, it's fast.
  But when I use polyline into the same loop between two circle like this :</p>
  
  <pre><code>var polyline = new L.Polyline(coordinates, {
      color: 'red',
      weight: 3,
      opacity: 0.5,
      smoothFactor: 5
      });
  polyline.addTo(map);
  </code></pre>
  
  <p>The performance decrease and it's really slow. The main problem is that sometimes there is no position between a range of time, so I need to draw a polyline to have something more visual, and no gape.</p>
  
  <p>Is there any way to solve this issue ? Thanks !</p>