Google is now penalizing sites for slow load times. One of the major reasons for slow load times is a large number of images. However, some subjects require a large number of photographs to explain concepts. Other blogs, such as photography blogs, are mainly images.
One solution is to optimize the size of the photographs prior to installing them on your blog. Ninety-two pixels per inch seems to be a reasonable standard for most photographs. This can be difficult to obtain if the photograph needs to be large or show fine detail, however.
Another solution is to optimize the photographs after uploading them to the web. There are many programs that optimize photographs by stripping meta data, optimizing the jpeg compression, and converting some gifs to pngs and stripping unused colors from indexed images.
However, most photographers object to having the meta data stripped from their photographs as that removes the copyright statement from the photographs. This makes it harder to prove infringement in case the photographs are scrapped.
One plugin that optimizes images without stripping the meta data is WP Smush.it. Available from the wordpress plugin page, WP Smush.it automatically compresses images by optimizing the jpeg compression, converting some gifs to.pngs, and stripping unused colors from indexed images.
Once installed, the plugin will allow you to manually bulk smush older, already loaded images, but will not go through and smush them automatically.
This is a definite disadvantage if you already have many images loaded. The bulk smush feature is slow and is considered a beta feature. However, this only has to be done once, so the feature is useful even though it is slow.