Good Answers here. I would agree that WordPress should not have trouble scaling with your needs if setup properly. You may also try cloning your site for testing purposes to revisit how your content architecture is structured vis-a-vis your various content types and add-on technologies (data, d3.js, ads). Doing this both from a front-end perspective and backend editorial workflow would probably yield productivity gains on both human and server/machine sides. Even if you decide to leave WordPress the the exercise would probably still yield useful lessons for your new choice of CMS.