You now have a script based on using low-resolution proxies. Before the final render takes place, switch the Globals parameter useProxy to the Base setting.
1.
Set the Globals parameter useProxy back to the Base setting by clicking the Proxy button on the top menu bar.
2.
Place your cursor over the Viewer and press the F key to fit the image to the Viewer.
The script looks exactly as it did before, except now the FileIns have loaded the high-resolution versions. That's the beauty of this system. You can quickly work out your composite using lower-resolution proxies and then, with the click of a button, switch back to your high-resolution originals. If this were a real job, you'd be ready to render. It's not a real job, so you're done.