d3.js : orthographic rotation optimization

Question

I made a map using an orthographic projection and I try to improve performance because the rotation is not smooth (around 6-7FPS).

It's a map of the world built with a topojson file (world-100m). I need to interact with country and colorized them so there is as many svg:path as there are countries.

After the loading I have an automatic rotation function launched using d3.timer :

autoRotate = () =>
  @start_time = Date.now()     # Store the current time (used by automatic rotation)

  d3.timer () =>
    dt = Date.now() - @start_time

    if @stopRotation or dt > @config.autoRotationDuration
      true
    else
      @currentRotation[0] = @currentRotation[0] - @config.autoRotationSpeed
      @projection.rotate @currentRotation
      redrawPathsOnRotationOrScale(@currentRotation, @projection.scale())
      false

redrawPathsOnRotationOrScale = (rotation, scale, duration = 1) =>
  @currentRotation = rotation

  @projection
    .rotate(@currentRotation)
    .scale(scale)

  @groupPaths.selectAll("path")
    .attr("d", path)

To understand why it was so slow, I made a profile record in Chrome and here is the result :

It seems the Animation Frame Fired is the slow part but I don't really know what it is. And when I open it, there is 2 GC Event (garbage collector ?) but nothing around... Do you have an idea what is happening during this 90ms ?

Any tips to improve the performance is more than welcome :-)

Thanks by advance !

By the way, it looks like this :

Answer 1

Try reducing the complexity of the SVG paths by adjusting the --simplify-proportion, -s or --quantization topojson flags. Browsers still have fairly poor SVG rendering performance, and with maps it really helps to reduce the number and precision of the points.

Answer 2

D3.js uses Request Animation Frames to perform timers.

From D3 documentation:

If your browser supports it, the timer queue will use requestAnimationFrame for fluid and efficient animation.

As I know it's the best approach to perform animations in modern browsers and I don't think you can directly optimize this part. Otherwise it seems that you call stack use selection_each that could probably be cached into a variable.