Having a fast site is really important:

"For Google an increase in page load time from 0.4 second to 0.9 seconds decreased traffic and ad revenues by 20%. For Amazon every 100 ms increase in load times decreased sales with 1%." source

These are two easy ways to make sure your Joomla site loads more quickly:

Turn on Compression

You can choose to send out your webpages in a compressed format. When you get a Joomla component it is often contained in a zip file. This enables the file to be much smaller without damaging the content in any way. You can do the same thing with webpages. In Joomla you just need to click "Yes" in the following place:

Site => Global Configuration => Server => GZIP Page Compression => Yes

There's also a great test to find out how much your site will benefit. According to WhatsMyIP.org, JoomlaTraining.com shrinks from 13k down to just 4k when GZip is enabled

Turn on Cache

Caching is another way to speed up your site. It stores files so that Joomla doesn't have to load the same elements every time. Why load the logo again on every page? Its best just to store it and reuse. It can turn on caching here:

Site => Global Configuration => System => Cache => Yes

The speed gains with caching can be remarkable. Last year there were problems with the cache systen we use here on one of our sites. We turned it off while we tried to bugshoot the issue. We also use Pingdom.com to track whether our sites are offline and also how fast they're responding. When we logged in later, there was a stellar argument for why caching your Joomla site is so important: the site loaded twice as quickly with the cache turned on.