The Cache-Control
header is added by Joomla itself on all backend and frontend pages. It's not something that each individual extension has the ability to change in its pages.
By default, Joomla adds headers to dissuade caching of its pages as it's supposed to generate dynamic content.
You cannot change that at all in the backend for the extremely obvious reason that backend pages must always be served fresh, not from cache, as their content changes all the time due to the administrative actions.
You can change that in the frontend of the site, by publishing the System - Page Cache plugin. This plugin sets the Cache-Control
headers to tell caching proxies (like Varnish, what SiteGround is using but won't actually admit; they did tell me when I visited their HQ and asked them point blank if that's what they are using) and web browsers to cache the page for a period of time. Please note that this does come with a tradeoff: your frontend pages WILL NOT show any new content when you update your articles, modules, etc from the backend of the site until the page cache expires. Moreover, if you have dynamic, per-user elements on your pages such as Joomla's login module you might see the wrong information (Joomla! will of course not send headers to cache the page once a user is logged in, but since the URL is the same as the public page SiteGround's SueprCache, i.e. the Varnish proxy, will still serve the cached public page, not the page the user needs to see).
Further to that, as SiteGround already knows, Akeeba Backup DOES NOT run on the frontend of your site, therefore it cannot affect your site's frontend performance. As SiteGround already knows, Akeeba Backup has NOTHING to do with caching headers at all anyway; it's a backup component, not an SEO or site caching component.
Maybe you should consider moving your site to an actually competent host. SiteGround seems to have put a lot of completely untrained help desk agents answering tickets, or you are the unluckiest person in the world to have your tickets replied to by all the help desk agents who have absolutely no idea what they are talking about.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
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