1. Regarding this issue, please try to disable all plugins except required plugin for JNews just for a while and see if the problem still persist or not.
2. Please try to clear your browser cache after making changes on the customizer.
3. Can you tell me more detail about the continuous load that you mention on above?
4. You can set up the sticky sidebar on customizer. You just need to go to Customizer then search sticky sidebar. For more detail please check this image https://www.dropbox.com/s/kphobx623t44def/Screenshot%202017-11-27%2010.08.42.png?dl=0 . Especially for the page, you need to set up the sticky sidebar directly on page editor. But by default, the sticky sidebar will be enabled when you creating a new page.