I've been doing some aggressive optimization in order to make large
find() operations faster on mobile devices.  I've currently got about
a 3x speed increase for a "SELECT *" on a 100-row, 15-column table:
http://github.com/mbrubeck/activejs/commits/master

Most of my changes should be safe (I haven't tested them rigorously
yet, but they pass all the unit tests).  But two of them introduce
incompatibilities, and might not work for everyone as-is:

http://github.com/mbrubeck/activejs/commit/dbb05530bb3c5b37a35b01de21...
Suppress all "set" notifications triggered by the model constructor.
This is a big performance improvement, but we should probably have a
way to turn them back on for people who rely on observe('set').

http://github.com/mbrubeck/activejs/commit/6cd1f9e1092c9953928340ae38...
Remove the ability to pass a field definition ({type:..., value:...})
as a value to the model constructor.  I couldn't find any code or
documentation that used this, or any reason you would want to (since
the "type" was just ignored).

See my commit log for more details and commentary.  I think I've
reached about as much performance as I'm going to get with local
optimizations to existing functions.  If I need any more speed, I'll
probably try some more radical surgery, like eliminating some steps
from the iterable->iterate->build->constructor pipeline.