Anytime you make a change (Add New / Edit / Delete) to the list of your categories, all the changes are instant, but you have to close your browser, restart it and reload your site, you will see all the changes reflected on the site. Needs a new clean session of the browser to show the updates. This is just for you since you are working on the site.
This does not apply to the list of menu items or products. All changes there are instant as well and do not require a closing/opening of the browser.