I've previously written about Any::Moose and suggested using it instead of Mouse in order to provide interoperability in code. You get Mouse unless Moose is needed and in that case you get Moose.

However, there are a few problems, mainly having some incompatibilities between Moose and Mouse (which has been drastically reduced to have as little side-effects as possible) and the load order being tricky. My original post relates to that specifically.

We now have Moo! Moo is very small, yet maintains much compatibility by simply not getting into the whole "metaclass protocol" thing, and giving you Moose-like attributes. Moo can also inflate properly into Moose objects, giving you what Any::Moose does, but correctly.

mst has written a very compelling post explaining how Mouse was started and how Any::Moose was designed in contrast to Moo, and why you should use Moo instead of Mouse or Any::Moose.

Moo is so awesome, I've started moving many of my modules to Moo. Dancer 2 is also based on Moo.

So, "can we have a smaller faster implementation of the basic parts of Moose?" - Yes, we can, it's called Moo.