Your theme (which is not one of the supported ones) seems to want to load all the images before it displays anything. With this many images you would really need to start showing things before all images are sent to the browser.
You can do the math. 1277 * 800 * 600 * 3 = 1,838,880,000 bytes of data not counting any overhead bytes. So, what do you thing the thruput of your server/web connections are? In addition, there will be processing overhead both on the server and the browser for handling the images.
This is one of the reasons most themes break the album down into manageable pages of thumbnails and show only a few per page.