optimization

Rule No. 1: You can’t optimize without benchmarking
Rule No. 2: Reduce memory footprint until paging stops
Rule No. 3: More connections is less connections
Rule No. 4: MySQL = RAM
Rule No. 5: Apache = CPU

Shows what CCK columns get used in a view filter or relationship and give you the option to add an index on it so the views query will run faster. Also can add indexes to core modules.

This module automatically runs CSSTidy 1.3 using the highest compression template when CSS optimization is enabled in the Performance settings.

Now, what i'd like, is something that looked for and flagged redundant rules in your combined Drupal stylesheets... this does not do that.

"making Drupal web sites load faster. 80 to 90% of the response time (as observed by the end user) is spent on downloading the components of a web page. Therefor this is also the part where optimizations have the largest effect."

http://stevesouders.com/episodes/

"wrote a simple Drupal module — the Episodes module — that could create simple charts to compare the average page loading time per day per geographic region."

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.

Increase realpath_cache_size to get rid of many many needless lstat calls.