performance

MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability.

PANTHEON Mercury 1.0, the quick-start server environment for those looking for the best in Drupal performance. You can launch Mercury now with our free Amazon Machine Images (AMI) or follow our install instructions yourself using any Debian Jaunty server.

script to figure out which functions/methods increase the memory usage a lot.

Drupal's page cache is capable of delivering blazing fast response times, but only when the cache is warm. And the reality for most small to mid-sized sites is the page cache is being cleared out far quicker than it's regenerated.

Our old friend Boost is suggested in the comments. We should simply make it standard.

The next thing to do is to identify the actual bottlenecks. yslow and firebug can help you for front end performance - which are often a bigger issue in the wild, but while Drupal core can make those problems easier to solve (reverse cache support, CDN support etc.), they need real world situations to be measured in, and the actual solutions are often site specific. So here I'm going to focus on what you can find on your local development environment - and three tools, devel module, ab, and xdebug/cachegrind.

Drupal's default behaviour is to render every single block on your site that's assigned to any region on every single page view, regardless of whether the region's content is actually being visibly printed out or not.

If you're doing a bunch of complex queries in those feature blocks, and you're not hiding the block by one of the following:

This patch can greatly reduce the number of database queries on every page load caused by URL path aliases. Groups of paths are cached together for each page and language allowing optimal cache retrieval of cached paths. Furthermore, a whitelist is built for uncached paths to intelligently limit the necessary database queries.

This patch was backported from Drupal 7.