If a picture takes a long time to load, most viewers simply leave. Many times we visit a web site that pauses before showing us anything, and then takes forever to load. Most times we leave. Images can considerably enhance a site, but they can also distract effective communication of information. Web site designers should know how to create the desired image with the smallest possible file size.
Animations can make a site a lot more interesting.
But they can also slow it down to a halt. Animations should be kept small both in size and number of frames. But this doesn't mean that pictures have to look small. There's no denying the power of a large image, if it can load up. Large images take up considerable screen space, but load up as quickly as an uncompressed picture one quarter of their size.