What do you mean by “handles 700” images? It displays 700 images? Do you have compound eyes?
There’s an official plugin called dynaview that claims:
* CSS classes that allow rendering to be deferred until the output is scrolled into view
So presumably if you could set that up correctly, the browser would only render what you actually have scrolled on screen. That should make the perceived time be faster. Maybe.
If you are loading external images, you could set the loading attribute of the image widget to “lazy” to enable lazy loading. I guess this should improve performances ?