WordPress backend (admin, edit post..) slow, frontoffice fast.

Hello,

I’ve developed my own theme using a few custom types posts. The frontoffice works great but the admin is really slow : 20 sec to load the page !

Admin page loading time :
– Total query time: 170,1ms for 96 queries (0,170073032379150s)
– Page generated in 21 000,0ms; (21,4154109954833984375000s); 99,19% PHP; 0,81% MySQL

Solutions :
– I’ve desactivated all the plugins, it doesn’t change anythin.
– If I change to wp defaut theme, the admin is fast ! => There is well a problem with my own theme…
– I’ve desactivated my custom types post,it doesn’t change anything.
– I’ve updated wp, it doesn’t change anything…

Do you have any idea how to fix this problem ?

Thanks in advance !