Any sort of delay when swiping likely had to do with the size of the images/content on the vertical. So if all of your verticals are PNGs, that is probably contributing to the verticals taking a little longer to load.
They way our system works is the next, adjacent vertical will start loading while viewing the current one but if you swipe fast enough it does not have ample time to load. You can try outputting your images as JPEG instead of PNG to see if that helps. Also, if you are using a lot of features like pinch/zoom, panning, slideshows or media on a single vertical this can add to the load time, so reducing these should also help.