Wordpress admin so slow related to theme

Question

My configuration - WordPress Version : 3.5.1 - PHP/MySQL Version : 5.3 - Theme : Sterling - Plugins : Seo Yoast ; BackWPup ; BulletProof Security ; Google Analytics for WordPress ; LayerSlider WP - Host : OVH - url : www.avoirunsite.com

Admin takes 40 sec to load.

I use a child theme of Sterling (a premium theme by True Theme)

Test results :

• Desactivate plugins : no effet
• Activate parent theme : no effet
• Activate another basic theme : solves the problem
• Logs : no error
• I have another site using the same theme and the same plugins, wp version and so on : no problem

Weird ...

Any Idea of what could cause this ? Thanks

Answer 1

I found the answer (True theme support helped me to find it): There is an "notify updates" option that contacts their server every time you load an admin page. It wastes a lot of time. Now, the page loads in 3 sec.