You can optimize your graphics used in the website and that will load your website faster than before. To reduce the size of the graphics you can use some of the following tools or websites.
1. Smush.it (Online)
This is from yahoo developer network. You can enter the url of the image need to be optimized and this will return those images in an optimized size.
Smush.it uses optimization techniques specific to image format to remove unnecessary bytes from image files. It is a "lossless" tool, which means it optimizes the images without changing their look or visual quality. After Smush.it runs on a web page it reports how many bytes would be saved by optimizing the page’s images and provides a downloadable zip file with the minimized image files
OptiPNG is a PNG optimizer that recompresses image files to a smaller size, without losing any information. This program also converts external formats (BMP, GIF, PNM and TIFF) to optimized PNG, and performs PNG integrity checks and corrections.
You can download a windows shell integration installer here, this will allow you to just right click on an image and optimize it.
3. Punypng (Online)
punypng is a free tool that dramatically reduces page load times by reducing the file size of an image without any loss of quality. You can upload mutiple files and can download all optimized images in a zip format.
PNGGauntlet is a .NET program that uses Ken Silverman’s PNGOUT to optimize PNG files. Many PNG files output by popular graphics software packages like Photoshop or even Fireworks are not as small as they could be – PNGGauntlet squeezes the last bit of size out of them. Furthermore, no information is lost during this process – the only thing that changes is the file size. Just select the files you want to optimize (or drag them onto the window), select where you want them to go, and click the button. PNGauntlet can also be used to convert JPG, GIF, TGA, PCX, and BMP files to PNG.