I'm working on some new code to speed up Thematic.
It would be great if you could checkout SVN version r549, install it on a live server, go to WP-Admin / Appearance / Thematic Options and hit 'Create Definitions'.
Please report the displayed status and if a directory 'settings' was created under your child theme's directory and if a file 'definitions.php' was created in this new directory.
The new code and some additional changes are already running on my blog. With the additional changes the 'definitions.php' is loaded and BLOGINFO_NAME is used instead of calling bloginfo('name') or get_bloginfo('name').
Depending on your feedback I'll extend the 'definitions.php' to cover all blog_info() calls.