Drupal 7 Really Slow on admin pages
If you can profile your site that's always helpful. https://drupal.stackexchange.com/questions/724/why-is-drupal-7-so-slow

https://groups.drupal.org/node/210683 - Older post but some patches have still not been committed.
https://groups.drupal.org/node/415883 - Speedups for the DB layer (caches mainly).

Because of windows checkout this post and this group
https://groups.drupal.org/node/242443
https://groups.drupal.org/drupal-windows