Hi,
If you force the container height with CSS, the images size won't be adapted anymore.
The only option would be to add custom javascript code to set the height of the containers based on the images calculated height on the browser. But that means that the images must be loaded before. And since you want to do that before the images are loaded, I don't see a good solution.
For your information, on my broadband connection, I hardly see the display issue. It lasts only a split of a second. And my connection speed is average in France.