The settings in .htaccess Maker (except HSTS) deal with static content such as CSS, images, JavaScript, font files, etc. Having them enabled is recommended, as they tell your visitors' browsers to keep these files cached on the client side, and they tell your web server to deliver them compressed which minimises the server bandwidth usage.
The HSTS option is not a caching option per se. It tells the web browser that this site is only to be accessed over HTTPS. The web browser remembers it, so next time a visitor tries to access the plain HTTP version (e.g. by typing the URL to your site directly, but without the https:// schema prefix) the browser will immediately go to HTTPS instead of doing a roundtrip to your site first. Highly recommended for privacy, security, and performance, but not a caching option per se.
Now, as you may have spotted, we didn't talk about dynamically generated content i.e. the pages Joomla creates - usually HTML, but sometimes may be other formats (RSS, Atom, XML, JSON, ...). This is where Joomla's built-in caching comes into play. Whether to use it or not depends on your site. If you have a site like ours where more than 90% of the site access is behind a login and personalised it makes no sense. If you have a mostly public site which doesn't use a login module (because that's also personalised after logging in!) do check if using caching makes sense. I have seen many sites which become slower when file-based caching is enabled. Conversely, I have not seen any commercial hosting environments supporting Redis or Memcached for caching (these are indeed fast, as they are memory-based). Benchmark your page access with and without cache to see if caching makes sense for your use case.
Do not enable Joomla's GZip page compression. It is slow, and causes problems when there is a PHP error on your site. The "Automatically compress static resources" feature in the .htaccess Maker already tells your web server to send HTML content over the wire in a compressed (GZip) format, as long as you have a web server version published in the last ~10 years. The compression applied by the web server is an order of magnitude faster than what Joomla! can do, and does not suffer from any adverse effects.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!
