Optimizing site performance

Overview

The purpose of website performance optimization is to increase the speed that visitors are able see your site. As websites become more complex, with databases, user authentication, multiple themes, and customized logic combining in complex ways to deliver each page, web caching becomes a vital tool for ensuring maximum site performance.

Want to clear the cache now?

• How to clear the cache after editing your site

How web caches work

The web cache works by storing complete copies of each web page. Pages stored in the cache are served to your site visitors immediately, bypassing the more time-comsuming dynamic page generation logic.

Dynamic page generation is more time consuming becuase each page must be recreated from scratch each time it is viewed. This typically involves retrieving relevant data from the database, combining the data with multiple design elements, attaching multiple style and javascript files, and finally serving the completed page to the visitor.

The problem with caches

There is one major disadvantage to using a web cache. When you update or edit your site, the changes will not show to visitors until the cache is rebuilt. This is because the cache continues to display copies of the pages as they existed when the cache was created.

For this reason, it is very important to "clear the cache" each time you make a significant edit to a page. Please see below to learn how to clear the cache. Once the cache is cleared, the site will begin to build a new cash, this time loading the updated page content.

Standard caching options

Drupal provides a powerful set of standard caching features, including the following: 

• cache page content
• cache page blocks
• cache custom views
• optimize CSS files
• optimize and compress Javascript files

Advanced caching options

For the majority of sites, the standard performance features are sufficient. More powerful techniques are available for very large or very active sites. If maximum optimization is required we can install additional performance modules, such as Boost, Authcache, Advanced Cache, Cache Router, APC, and Varnish. Please note that these are advanced techniques. In some cases they require the use of a Virtual Private Server (VPS) or a Dedicated Server.

How to set site performance configurations

1. Login using your administration account.
2. Point your  browser to Administer > Site configuration > Performance
3. Select Caching mode: Normal
4. Enable page compression.
5. Set a minimum cache lifetime. Please note that CRON must be properly configured for this setting to work. The optimal cache lifetime is different for every site. Please contact support if you need help with this setting.
6. Enable block compression.
7. Enable CSS and Javascript optimization.
8. When you are ready, select Save Configuration.
9. If your site produces errors when using caching, you can quickly turn all caching features off by selecting Reset to Defaults.

How to update the cache

1. Login using your administration account.
2. Point your  browser to Administer > Site configuration > Performance
3. Scroll to the bottom of the form and select, Clear Cached Data.
   

Please Note: If your account has access to the Admin Menu, there is a handy set of cache update links in the far left menu under the Drupal icon.

More Information

• CommunityGrove Guide: How to clear the cache after editing your site
• http://drupal.org/node/326504
• http://www.mnot.net/cache_docs