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Recently we have discussed Data URI schemes previously and were trying to develop a patch for Drupal 6 that will create optimized CSS automatically. The latter solution break IE 6/7 and probably other browsers that do not support data URI schemes. Today I have a better patch that just provides a workaround for IE 6/7 (yes, these browsers won't gain any performance improvement using this patch).

We have discussed Data URI schemes previously and how they help reducing number of HTTP requests for CSS images.

Today I have developed a patch to Drupal 6.x core that will inject images into CSS file when Optimize CSS files option is turned on. This patch embeds only images less then 1K in size. Follow the comments for more information:

Long time ago in early 2006 I have developed my Drupal's cache.inc shared memory based implementation. APC implementation was done after some time. But these contributions to Drupal 4.7 (or was it 4.6) were never published.

Years passed. Things happened. I realized open-source to be one of the greatest things happening to me. Now I can't imagine writing Drupal module on my free time and not to share it with community.

So today I would like to present my new Drupal 6.x contribution - Cache module.

Drupal 6.x core adds ability to change cache handler implementation by specifying another $conf['cache_inc'] in settings.php:

    case DRUPAL_BOOTSTRAP_EARLY_PAGE_CACHE:
      // Allow specifying special cache handlers in settings.php, like
      // using memcached or files for storing cache information.
      require_once variable_get('cache_inc', './includes/cache.inc');

or specifying another $conf['session_inc'] session handler implementation:

    case DRUPAL_BOOTSTRAP_SESSION:
      require_once variable_get('session_inc', './includes/session.inc');

My idea was to add ability to change path.inc implementation by specifying $conf['path_inc'] setting in site's settings.php file.

Data URI scheme can be used to include images in HTML document or CSS file. This gives you ability to save several HTTP requests for image files thus making your HTML pages open faster. Data URI scheme feature works mostly in all modern browsers except IE6 / 7 (special MHTML protocol can be used for IE instead but is not discussed in this article).

PHP owns special Xdebug extension that can be used for debugging and profiling PHP code. Profiling means determining bottlenecks in your scripts and visualize them in some external application (we'll use KCacheGrind through out the page).

In this article we'll give a real example how profiling can help to improve your PHP web-site's performance. We will profile Drupal 6 core.