A layout have up to 6 different layers starting with the default Theme and finishing with Conditional Formatting. Every time the layout have to be rendered it starts from it´s default Theme down to last layer Conditional Formatting. If possible try to avoid Conditional Formatting to have a more optimised layout.
That will not fix your problem.
Have you tried to just load the thumb nail of the picture? That would make each image load a lot faster.
I try to minimize conditional formatting, but in some instances, it is the only way to achieve a desired UI feature.
My issue is not the speed of the layout rendering. My issue is that the wrong image renders in the container field until I manually refresh. How would a thumbnail fix this? And how do you mean load a thumbnail? Do you mean have another field with a smaller version of the image? Or is there a thumbnail feature I don't know about?
Maybe you have come a product issue that I am not familiar with.
"To speed up the rendering of images in container fields, FileMaker Pro by default generates image thumbnails and caches them in memory."
When I have a container field that user can drop a file/image in I use OnObjectModify that sets another container field using the GetThumbnail() function. That is the field I show on the layout and if user want to reach for the container I open up the real file/image