Large images (that is, any much larger than 20K or so) can take a frustratingly long time to load. If you have several large images on your page, the user might give up and move elsewhere before your images load. To keep the user's interest and give the user an idea about what the wait is for, try saving those large images as interlaced GIFs or progressive JPEGs, which load in stages.

Here's an example of each.

All you need to do is to select the proper Sub Type in PSP's Save As window. For a GIF, select Version 89a - Interlaced. For a JPEG, select Progressive Encoding.