I know you guys are working hard on this, but here's some more test data.
I ran the cocoonjs box2d demo on my 5 year old android (droid incredible 1GZ - 512MB - android version 2.3.4) and get a solid 40 fps when adding 60 of those asteroid objects.
Next I ran the construct 2 Angrybirds demo - it got down to 2 fps.
A simple ball and ground gave me about 20 fps.
I hope some progress is made on this topic.
Keep up the good work!