A key feature of Medica and Zen Grid Framework v5 themes is it's focus on performance. Out of the box Medica scores in the 90s using google page speed tests with some additions to your htaccess file.
We have spent a lot of time fine tuning the way assets load in the template as well as to create some flexible options for users to tweak the way that their template performs.
2. In the template settings/assets.xml file you can also specify files that you wish to add to your css or js files. This is a more developer orientated option but is an equally valid way of adding additional assets to your theme.
Reusable theme css files or a css file for each template theme.
Theme files created in the template admin can be assigned to other instances of the template using a different configuration. This means that even though the second template instance may be using different settings it's main css file becomes a cacheable object because it is not load anew for each page.
Always load the default css
It is possible however to override this behaviour and always load the default (css/template.css) file. This setting is applicable for users who want to bypass the builtin theme options and compiler and either use a 3rd party compilation program (like codekit) or write their css using a different preprocessor language or using good old fashioned css.
In order to make this change for the template you need to navigate to the settings panel in your template and enable the Load template.css file in the debug settings.
Gzip is a technique that can be used to provide compression to your js or css files. Gzipped files are served in the browser via php files and then de-compressed in the browser. Gzipping assets can lead to a performance boost depending on other server settings and the number of assets loading on a page. Gzip is recommended on sites that do not already use gzip compression in their htaccess file.
Use a cdn for the core files
A Content Distribution Network or a CDN can be used to improve your site's performance for two main reasons. Assets loaded on a site from a separate domain are able to load asynchronously (eg while other files are also loading) in the browser. This means depending on the server and users internet connection the site will generally load faster. CDN's also offer location specific loading of files so that the user downloads a copy of the files from a server that is physically the closest to them within the network. This can also help to cut down on valuable seconds or micro seconds when considering the site load.
Use a cdn version of jQuery
zgfv5 based themes also have the option of replacing the core Joomla version of jQuery with a different version specified by url in the template settings. This feature makes it possible to use any of the hosted jQuery versions from Google, jQuery etc and therefore take advantage of previously cached instances of the library in the users browser as well as utilise the same CDN principle outlined above.