Speed enhance your visitor experience and also have a positive effect on your site position in Google Search. Here is some information about Joomla site speed.
Server Side Optimization of Joomla site
Joomla has a built-in cache plugin, which caches the whole joomla page. When this plugin is enabled, first time it caches and next time(s) it just deliver from cache. It does not go to each Joomla component for getting the output. So not K2 and Virtuemart. Definitely it is fastest joomla page creation on server.
This works fine for totally static Joomla sites. But if you have anything dynamic on your page, cache plugin mostly give the wrong output. That is because it does not process anything at all. So, if cache plugin is enabled and your site is totally static, you may set a cache time in global configuration something like 21600 for 15 days and get a fast output of Joomla page's html. In this case you don't need anything for server side optimization. This is because Joomla page created on server once and remains same for next 15 days or so.
As this is not the case with most websites, you need to disable cache plugin. If cache plugin is disabled, there is a need of our K2 listings Speed up or Virtuemart Speed up plugins. Our plugins, caches only the component content (K2 or Virtuemart) and not the whole Joomla page. So, other parts of the your Joomla site may contain dynamic content.
So the bottom line is;
1) System Cache plugin enabled - Fastest - No processing at all. Page delivered from cache but static.
2) System Cache plugin disabled - Slowest - Everything processed every time. Also the K2 and Virtuemart content.
3) System Cache plugin disable but K2 Speed Booster and/or Virtuemart Speed Booster enabled. Best in most cases. Our Speed plugins deliver from cache but Joomla remains dynamic. Means, speed without any compromise.
Client Side Optimization of Joomla site
Regardless the method you use for server side optimization, The client side optimization is equally important. It is actually arranging your html code effeciently that client browser can download it as fast as possible. Various tools are available to check your Joomla site speed for client side optimization. One we recommend is from Google. It is called Google Page Speed checker. There is an online version available here:
A firefox extension is also available for that and great for testing the speed score of your Joomla site.
We have a plugin to automatically arrange and optimize the html produced by your Joomla site. It is called SpeedBooster for Joomla. It does many other things including css optimization, Image optimization and more. You can have a free, fully function trial also.
If anything requires further clarification, please contact us. We also offer custom solutions to speed up your Joomla site.