Hello!

the only way you can do that right now is to make an article 'featured'.
In the extension, you can filter items and make the featured ones to show first always.

The settings for the featured articles is no different than the rest of the items in the module or menu item you have created. 

The first time articles are loaded, thumbnails are created (if you chose to process the pictures in the extension). If your images are large, the server needs more processing power to create those thumbnails. But this only happens the first time thumbnails are created.

Make sure the extensions' advanced parameter 'reset pictures' is set to 'no' or that the 'site mode' parameter is set to 'live' (a new feature of the extension).

If you have trouble with the creation of images, make sure they are reasonably sized. The larger the image, the bigger the amount of memory needed for processing (it is actually exponential and png images are more demanding).