It just so happened from time immemorial that the search page Google is a white field with a logo and a search bar. Nothing extra. However, now users have the opportunity to personalize it as they wish.
It's about the search page. Googleand not about iGoogle. The decision to add the ability to change the background image was clearly borrowed from bing. That's only if the search engine from Microsoft background images are loaded randomly, but here they are entirely dependent on the user's desire. There are three ways to choose from: upload an image from your computer, use an image from a personal photo album picasa or an image from a public photo album picasa.
As assured Google, uploaded pictures will in no way affect the speed of the search engine. The picture will simply be loaded into the bowser cache, so there should be no problems loading it.
At the moment, the ability to change the image is still available to residents of the United States and some other countries. But gradually it will be available to users around the world. To change the image, a special link will appear in the lower left corner. If you don't have it yet, it means it's not available in your region yet.