get high quality images in background of websiteswithout compromising load time?

i am making a website where i want one huge image to cover the complete background. I have seen many websites where the images in the backg开发者_开发知识库round look to be of very high quality and still the pages load really quickly. How? for example look at this link http://g2geogeske.com/menus how can i achieve images with quality like these without compromising with the load time. Also if anyone knows of any tutorial or site which explains this please post the link to thanks.

even after being so big its just 170 kb(backgroung in link).my images are at about 700 kb and still look of lower quality then the one in the link. Am i missing something. some trick or anything??

You want to know how to compress images? Go download a decent image viewer (Irfanview) or editor (Paint.NET) and go to town! The background for the site you linked is a 171kb jpeg file; that's peanuts for a half-decent internet connection.

usually when you save an image as a jpg, you have the option to specify a 'quality' rate. If you look at the image in the site you linked, the background image, even though it's really big, it's only 170K. To me, the magic number to save a JPG is 90% quality.
ADD: Also, if you use Irfanview, you can add a plugin called 'RIOT' that compresses images even further (I think you can also get it as stand-alone or something) http://luci.criosweb.ro/riot/