Optimising:
Optimising images for the web is very tricky. You have to get the right balance between filesize and picture quality. Look at a webpage,  you will be able to see that most of its load time comes from images. Your website will be ridiculously slow if you don't drop the sizes of the images. There are three areas where bytes can be shaved off your graphics: bit depth (number of colours), resolution, and dimension.You don't need really expensive graphics editors to reduce the sizes of your images, there are plenty of free utilities that will do the job.