Optimizing of DB resources I'm pretty excited about Drupal capabilities in general and consider it as probably the most solid free CMF with a really powerful API. One of the things I'm concerned about is the resources it takes. A basic installation with localization generates about 90 database tables (WordPress generates  11). Can this be optimized or, if it cannot be, does it really matter, does it affect performance?
Table count is not an indicator of optimization. It is actually opposite of what someone might think. Good database design breaks data up into multiple related tables that are kept small in field count. Drupal core has a very efficient relational database design compared to WordPress. I have experience with both platforms and your statement highlights what you must realize about Drupal. Drupal really is a content management framework, WordPress is a content management system. They are vastly different in their capabilities.

So to answer your question plainly, no optimization is required. It already is optimized for a relational database.

As always, choose the right tool for the project. Even though I am a Drupal developer I have recommended Wordpress to several clients. Because their needs and requirements could be satisfied with a simple Wordpress site.