Why is putImageData so slow?

Question

I am working with a relatively large Canvas where various (complex) stuff is drawn to. I then want to save the Canvas\' state, so I can quickly reset it to the state it now

Answer 1

In Firefox 3.6.8 I was able to workaround the slowness of putImageData by using toDataUrl/drawImage instead. For me it's working fast enough that I can call it within handling a mousemove event:

To save:

savedImage = new Image()
savedImage.src = canvas.toDataURL("image/png")

The to restore:

ctx = canvas.getContext('2d')
ctx.drawImage(savedImage,0,0)