Performance issues in the queue

Three weeks to go before the code freeze. Here are some issues to focus on:

• Split up the cache table: http://drupal.org/node/72290
• File based caching: http://drupal.org/node/45414
• Seems the above can be turned into a module because of this patch: http://drupal.org/node/67675
• Robots.txt patch: http://drupal.org/node/75916
• Set cached pages to a reasonable date: http://drupal.org/node/65017
• Better caching (cacheable blocks): http://drupal.org/node/72617
• Don't select uid=0 when starting sessions: http://drupal.org/node/76931
• Let admins set watchdog logging level (saves lots of queries): http://drupal.org/node/77875