Tree loading slow after PHP update

Hello, my hoster upgraded to: PHP Version 5.4.36-0+deb7u3. Since that after login the resources tree takes a very!!! long time to load. I'm using modx 1.0.15. I have that problem in two projects that have a lot of articles in the tree. One of them has over 3000. But everything was working fine with the former php version.

Can anyone help? Thank you!