The WordPress core team cares both about user experience and about performance. Here is further proof.
Our allowed attributes rules in kses.php create a large number of empty arrays. These can all be replaced with true instead. This reduces memory usage by 62 kilobytes – not huge, but it all adds up.
duck_ is completely right. Every spot that the core team can find to improvement memory usage, helps everyone.
If you’ve used WordPress over the past few years, you should know that a lot of web hosts run into memory limit issues and cause an “out of memory” error. This can be fixed by raising the allowed memory usage in Apache/PHP, but some hosts don’t allow it and can make it difficult to run WordPress.
The WP Development blog recently announced that they are working on performance for the next major release, WordPress 3.4.
via WP Trac #20017
