Color Section Homepage Image Loads Huge Then Resizes to Screen

hi – great theme – I’m literally on about the 30th purchase. There is an annoying thing happening with the full screen Color Section on our homepage. On Mac Chrome, the image first loads very large and then quickly shrinks to fit the screen. On Mac Firefox, a purple/TV static appears quickly before the image does. The page itself is kind of large, so I thought perhaps it was affecting page load speed. But I isolated the element on a new page with nothing else on it and it still happens. It’s really quick, but definitely annoying, and does not happen after the page gets cached – only on first visit. If I swap out the image, it still occurs.
Any ideas or help would be greatly appreciated.
Kind Regards,
Doug