Switch on Caching to give your Joomla website an instant performance boost.
What is a cache? Wiki says:
A Cache is a collection of data duplicating original values stored elsewhere or computed earlier, where the original data is expensive to fetch (due to slow access time) or to compute, relative to the cost of reading the cache. In other words, a cache is a temporary storage area where frequently accessed data can be stored for rapid access. Once the data is stored in the cache, future use can be made by accessing the cached copy rather than re-fetching or recomputing the original data, so that the average access time is lower.
What does this mean in terms of Joomla? Instead of hitting your MySql database with same queries over and over again, your data is stored to a local storage (in the Joomla cache directory) and retrieved from there, instead of from the database. This means that your database will perform better, and your website will feel faster, and be able to support more simultaneous users.
Please note, that this is different from browser caching - browser caching is something which is instructed by the web server (but done by the local browser). This is actual caching of the resources and HTML created on the web server. If you want to read more about how to leverage browser caching read this article here.
Joomla 2.5 and Joomla 3
Activating the Cache is straightforward. From the Global Configuration, click on System Tab, and on the right-hand side, there is the Cache Settings section. Click ON - Conservative Caching or ON - Progressive Caching in the Cache Settings, and put a reasonable amount in minutes (60 minutes should be quite good for most websites). Once you press Apply, Caching will be enabled.
Point of note:
When enabling the Joomla cache, you may notice that your "Hit Counts" are no longer increasing on each and every hit. Essentially, since you're storing a copy of the content for some time, the Hits will only increase each time the cache expires. Although this might sound like a disadvantage, we believe you should be completely ignoring hit counts regardless of whether you enable the Joomla cache or not. Hit counts are skewed and inaccurate for various reasons
1. They are inflated by your own hits
2. They are inflated by bots, crawlers, and other "unreal" or "ghost" visitors, these are not actual visitors to your sites. They are just scripts doing their robot tasks. Thinking of these as actual people reading your posts will lead to an unrealistic scenario
3. Services such as Google Analytics are much more accurate at handling scripts and creating a detailed analysis and profile of your website visitors. It will do you much more good if you use a script such as Google Analytics for this. You can use our Joomla Google Analytics plugin to do this.
As you can see throughout our site, we've disabled most places where Joomla hits appear, because we believe these are useless, literally a waste of resources. If you want to know who is hitting your site, use Google Analytics. If you want to impress your visitors with the number of page views you've got, add some social buttons. They're much more prone to bring plenty of traffic, and of course, they are actually accurate.
Activating the Joomla Cache is also straightforward. From the Global Configuration, click on System Tab, and on the right-hand side there is the Cache Settings section. Click Yes on Cache Settings, and put a reasonable amount in minutes (60 minutes should be quite good for most websites). Once you press Apply, Caching will be enabled.
The standard Joomla cache is enabled from Site > Global Configuration > System > Cache Settings (or Site > Global Configuration > Cache tab for Joomla 1.0), and mark it as enabled.
Though there are components written for caching the out of the box caching will give your website an instant boost.