Panzoom JS very slow on initial load

I am using the panzoom.js library to pinch-zoom / wheel-zoom a map image. It works well. However, when the page loads with an empty cache and you attempt to zoom-in with either touch pinch or mouse wheel, there is a very noticeable lag and the image slowly catches up to the zoom. Once zoomed in, you can then very quickly zoom the image in and out and its very responsive. Is there anything I can do to achieve this fast zoom response right away. I have tried only displaying the image after page load and using smaller file size images etc. Nothing seems to work. Can anyone suggest a hack I might be able to try? As it is now, its very frustrating for the user, especially on touch.

Here is my test page: https://cryptopixel.app/testmap

The initial panzoom.js instance code is:

const elem = document.getElementById('map_inner_cont')
        
window.panzoom = panzoom(elem, {
        //zoomDoubleClickSpeed: 3,
        autocenter  : true,
        bounds      : true,
        initialZoom : pz_scale,
        animate     : true,
        minZoom     : 0.05,
        maxZoom     : 2,
        onClick(e)     {
            touch_feedback(e);
            map_click(e);
        }
})