Site is slow when visiting admin pages I turned on Devel query log and at the bottom of my pages it shows the log with the number of executed queries and ms. When i visit any admin page for example /admin/appearance i have following entries in my query log:

 _update_cache_clear 73ms DELETE FROM cache_update WHERE (cid = :db_condition_placeholder_0) 

DrupalDatabaseCache::clear 81.9ms DELETE FROM cache_bootstrap WHERE (cid = :db_condition_placeholder_0) 


As i know, it shouldn't be more than a 5ms. I am using Xcache on my server with 16gb RAM. What's the culprit?

PS when i am visiting non-admin pages they all are loading very fast.
by default drupal cache pages for anonymous user, and it is usual that visiting page bye anonymous user be faster than login users,also in admin page we have more load that front-end page
The is a property of durpal. admin pages have more forms and more proccess.