Poor Performance if zooming in on large timeline.

If you have a timeline that covers ~100 years and you then try to zoom in to a day scale. The performance of all aspects of the timeline get very poor.

This is a simple test json example that reproduces the problem for me in chrome:

{
  "events" : [
    {
      "start_date" : { "month" : "1", "day" : "1", "year" : "1901" },
      "end_date" : { "month" : "1", "day" : "1", "year" : "2001" },
      "text" : { "headline" : "Long Event"}
    }
  ]
}

Start by reproducing issue 538 in Chrome with the provided JSON containing a 1901–2001 event, then profile the timeline while zooming from the 100-year range to a day scale. Trace which timeline operations cause the slowdown across zooming and related interactions; done means the timeline remains responsive for this example at day scale.