An image optimizing plugin can help reduce the size of the images on your site, often without impacting the quality of the images. This can help reduce the size of your site, and speed up the load time as well. When installing a new plugin it is always recommended to find a plugin that is regularly updated.
Note: EWWW Image Optimizer is an example of a plugin that can reduce the size of your images.
Once installed the new image optimizing plugin should have its own section in the left-hand menu. Locate this menu to begin using your new plugin.