Galleria: Load first image earlier
Galleria: Load first image earlier

Galleria triggers loading of the main gallery iamge via javascript
which has two problems. It only triggers the load when javascript
has been processed and loads it at the same time as the second and
third image which means it's competing with background images for
bandwidth. We know that the first image will always be seen, so
trigger a load in the document rather than waiting for js to do it.

kontza/sigal,kontza/sigal,kontza/sigal