Hello I am French, I'll try to make myself understood.
I use ZP for 5 years on my site no problem.
I installed 10 ZP on my site with different databases.
The problematic part is this:
http://www.caboucadin.com/activite-maternelle/

Sometimes the page does not display completely. I found the solution by making F5. I even wrote in the description. But users do not read and leave my site.

Can you help me please
thank you in advance
cordially
Mr caboucadin

Zenphoto version 1.4.3.4 [10988] (Official Version) upgrade
Currently used locale: fr_FR.utf8
Currently used theme: Default
PHP Version: 5.3.16

What do you mean by not displaying completely exactly? Are there errors in the Zenphoto and server logs? And if which? The link you posted looks normal to me.

Generally, please understand that we can only really support the current release (1.4.4.1b currently).

Pressing F5 makes the browser refresh the page, so I would assume your site is not supplying the HTML quickly enough for the browser. When you refresh your browser page, some of the items are already in the browser cache, so they do not need to be fetched again.

Best guess it that this is a problem either with the speed of your internet connection or the speed of your server.