Apart from making sure your theme is well written and your site is on a fast server, one of the biggest gains can be seen from implementing caching. What this does is create a static or fixed version of your website. So when visitors come your site it is not generating fresh content via the CMS (Content Management System). This reduces the load on the server and often dramatic decreases the time a page takes to load.
Different methods of caching
There are of course different methods of caching. From the perspective of our platform caching can be implemented in any one of three places. That is on the website (via a plugin), on the load balancers and/or web servers or via a CDN (Content Delivery Network) like CloudFlare.
Using a CDN
A CDN caches your webpages on the providers servers. Most large CDNs have a global distributed network so it is likely that a copy exists close to your visitors. So in effect you get two advantages by using a CDN. Firstly caching and secondly a geographically disperse network, that is likely to have a cached copy of your site. This decreases the load time as the site is coming from a much closer location to your visitors.
Reverse Proxy/Load Balancers
Since we run a clustered web server environment we use load balancers in front of our web servers. These also cache pages on top of load balancing. So if your site doesn’t change often there will likely be a cached copy of the content on the load balancers.
The third version is to cache via your website. WordPress for example has many cache plugins and it is simple matter of choosing one that works well with the theme you are using. From our experience some themes do not work well some certain caching plugins so you are well advised to test the plugin before deploying it to a live site.
When Caching Doesn’t Work
One big push at the moment is activating SSL (Secure Socket Layer) on websites. While this has that advantage of better securing your website and helps to keep Google happy it has the downside of being not easily cached. So if you are using SSL then having a caching module on your website would be advisable.
Installing a caching module for most websites is a no brainer. Most sites do not change very often, so a cache will make a big difference.