Speed
-Graphics really slow down
page loading time.
-The larger the graphics, the longer the wait.
-compression is a must to keep images smaller.
Compression Types:
JPEG
PNG
GIF (LZW) (limited to 256 colors)
JPEGs are usually larger than GIFs
PNG is great, but new and not supported by older browsers.
-another thing you can do while your visitors wait, is to use progressive
display, often called interlacing. This
will partially display the images as they are loading.