On any typical website, smaller images = faster loading time and lesser bandwidth consumed. It is really important to find an optimal balance between image quality and image size. Anything "un-optimized" image will parasitically suck your bandwidths and cost you a bomb if you are paying for these bandwidths. Also if you are on a free Helio hosting plan and have a popular site you may find you are out of bandwidth . If you really liked to reduce images file size and doing it the quick and easy way, I thought you should know Smushit.com.
Smush it can probably do either a big job or small job of reduceing your image sizes. Just a tip if you have a big png or gif file try converting it to jpg and see the size
well the site is here Smush it