Well, expanding on my last edit, I got to findings a bit faster than expected. It’s definitely doable:
The gif makes it look a bit worse than it actually is. It’s not perfect yet, but I think there is a manageable way using a web socket. I figure I should toy around with compression a bit…
Sorry for derailing this thread a bit from its title, but i think it touches on the same issue of large-data transmission between JUCE and the webapp that displays in the WebBrowserComponent 
I can report that websockets are definitely a super-fast way, if the Resource Provider is not enough for some reason, but they’re also quite hard to implement. I might share something, if I make the final jump to JUCE 8 and it’s worth investing more time into the code.