THe thumbnails take a long time because the image file is huge. I took them with my 6 mega pixel camera. I think I will shrink them into actual thumbnails so they load faster, would that be a thing worth changing?
Any images you post to the web should be optimized to a reasonable size. Reasonable in both file size and dimension. In a program like Photoshop or similar, re-size your image to something like 600 x 400 pixels, so that even someone viewing at an 800 x 600 screen resolution can easily take in the whole image. Now that you have an image with reasonable dimensions, reduce the file size considerably. Photoshop will easily let you get the file size well below 100kb without losing visual quality with the ‘Save for Web’ feature. You can get the file size much smaller than that while retaining good quality, but at the very least try to make sure you never exceed 100kb.
Hope that helps. Good luck with the site. Looks quite good other than the image size issue!