Hi there,

we just upgraded from 2.0 rc to current version and just realized why we had to roll back (had strange performance issues):
We're reading from a Hash field very often and this was just dragging down our whole system.
I traced it down to this part in fields#create_accessors:

              read_attribute(name).tap do |value|
                if value.is_a?(Array) || value.is_a?(Hash)
                  changed_attributes[name] = value.clone unless attribute_changed?(name)
                end
              end

the #attribute_changed? calls aswell as the #clone call seem to slow down everything.
I'll keep you posted with additional details.