Keep the images in WordPress a nice size – Google like it and will rank your website higher.
If your site is a little slow to load its often caused by large images. They are easily reduced within WordPress – a good size is 400 to 1000 pixels wide. Faster loading site are ranked higher as this produces a better visitor experience for your site visitors – Google like this.
Do this: Go to Media, select images, select the month (I start with the oldest), edit and re-size, click Scale.