Facer is currently the heaviest app I have on my smartwatch (78mb), double that of Wear Os and only surpassed by Google Play Services. I guess that is because the app saves the last 10 faces synced (20 for premiums). This means a more than considerable percentage in the available memory of smartwatchs today.
On top of that, based on my experience as a user and designer, the simpler faces load faster and work better.
Faces that have many elements (especially sequences of images) take longer to sync and sometimes fail completely to do so (please read the comments of my CFW Weather Animated).
I can not assure that the main responsible of this problem is the total weight of the face and not the particular operation of some elements, but certain tools would be good to help us control the total size of the face ...Thanks