As a content management system (CMS), Joomla can sometimes end up being the slowest of them all.
Firstly you need to understand a stripped version of Joomla! doesn’t run slow. It has no weaknesses both search engine wise and, in terms of page loading speeds, the pages load quickly and the code is clean.
The issue with Joomla! is instigated once web designers get their hands on it. This is only prevented if a professional company conducts the project though, if not page speed shines through as a serious problem and the search engines quickly turn on you.
Most components have external references to them, meaning suddenly each web page with those components is suddenly slowed down because it has to search and read more files before the page can load. Try stripping the CSS files into just a view militant type files, place javascript files into one main one. This suddenly can mean that you go from 9 external references to 3 or 4.
Have you compact and repaired the MySQL database it runs off? Open up PHPmyAdmin and select all the files by clicking “Select All” on the main page of the database menu. Once you’ve selected them all click on “optimise” and follow by clicking on “repair”.
Now that you’ve optimised the database and reduced external files the speed of the site should be improved dramatically. The only trick now is to look at the images and shrink them to the right size to be displayed. Often, on Joomla, when users create content and upload images the images aren’t at the relevant size due to people shrinking their display size rather than their actual size.
Each image on a site is normally shrunk when being placed on display. Fixing this issue can save up to 60% of the image size for each picture. This means if you have 3 images on the front page of your website than you could potentially save 20kb.