This could be a solution, though 4/5 is maybe too few, I'd say around 10.
But on the other hand I am not sure that having more "contributions" to process is a good idea, even if they are smaller. It makes the "queue list" more difficult to manage.
If you think to the "Alarm für Cobra" topic with lots of pictures, the problem was not the number of pictures but the fact that they had to be resized, which takes time.