I don't know the exact count for this Photo.get(...) call but it can
be around 2,000.
If it's related to deserialization then my guess is there's a high
overhead due one of the Photo class properties: it contains a
dictionary for EXIF metadata serialized as text.
class
Looking at the implementation of ReferenceProperty, I was able to
rewrite my DictionaryProperty with a similar design and lazily
deserialize the dictionary, and confirmed it works as expected. The
function make_value_from_datastore is no-op now, no more eval() calls.
But it makes no visible
