WP's default 90 is too high. Turn it down & make your site load fast!

60 – 80 is really where this should be set, depending on a few factors. This plugin makes it easy to set it. Then if you need to resize old images, use the suggested Regen Thumbnails to re-create the thumbnails with these settings. I took a site from 110MB down to 85MB by running its over 1k images through this. All those thumbnails really add up. Great plugin for optimizing images on WP.