How does 2D drawing frameworks such as Pixi.js make canvas drawing faster?

Question

I found a bunnymark for Javascript canvas here.

Now of course, I understand their default renderer is using webGL but I am only interested in the native 2D context performance for now. I disabled webGL on firefox and after spawning 16500 bunnies, the counter showed a FPS of 25. I decided to wrote my own little very simple rendering loop to see how much overhead Pixi added. To my surprise, I only got a FPS of 20.

My roughly equivalent JSFiddle.

So I decided to take a look into their source here and it doesn't appear to be that the magic is in their rendering code:

do  
{
    transform = displayObject.worldTransform;
            ...
    if(displayObject instanceof PIXI.Sprite)
    {

        var frame = displayObject.texture.frame;

        if(frame)
        {
            context.globalAlpha = displayObject.worldAlpha;

            context.setTransform(transform[0], transform[3], transform[1], transform[4], transform[2], transform[5]);

            context.drawImage(displayObject.texture.baseTexture.source, 
                               frame.x,
                               frame.y,
                               frame.width,
                               frame.height,
                               (displayObject.anchor.x) * -frame.width, 
                               (displayObject.anchor.y) * -frame.height,
                               frame.width,
                               frame.height);
        }                      
    }

Curiously, it seems they are using a linked list for their rendering loop and a profile on both app shows that while my version allocates the same amount of cpu time per frame, their implementation shows cpu usage in spikes.

My knowledge ends here unfortunately and I am curious if anyone can shed some light on whats going on.