The prototype is currently very slow and probably unreliable because it's utilizing a service that is on labs. When the service is moved to production, update the prototype to use it.
Instructions from @Jhernandez :
The printing on the proto is just opening a window with a URL to the printing service.
This is where the printing service urls are generated:
So pointing somebody there and modifying https://github.com/joakin/protowiki/blob/master/src/api.js#L35-L37 to give the url to the new service back should be easy.
Keep in mind that the flashcard is generated by printing the prototype itself on the /flashcard/Title url (http://flashcard-1.surge.sh/flashcard/Cat) so if the production rendering service doesn't allow passing in arbitrary urls as the wmflabs one does, then we'll have to use the wmflabs one for the flashcard, but we can move the pdf download one to the production service.
If I'm not making much sense please ask more and I'll try to clarify!