A lot of new web frameworks don't work that well scalability-wise. Many design decisions don't work that well. Too small sql queries and so. Mostly because of something called the active record pattern. There's a one-on-one mapping between objects and database tables. With the help of sqlalchemy, turbogears 2.0 uses a better mechanism: eager, lazy and dynamic object graphs. The data mapper pattern. Sourceforge is going to use/is already using turbogears for most of their pages!

Retirado de http://reinout.vanrees.org/weblog/2009/07/01/ep-turbogears.html, grifo meu.

Atualização em 17/07/2009: Mark Ramm publicou em seu blog alguns detalhes desta implementação em http://compoundthinking.com/blog/index.php/2009/07/16/turbogears-on-sourceforge/