Javascript issue on xwiki 8.4.4 and FF 52.3.0


I use Firefox ESR 52.3.0 (64 bits on Debian stable and an http proxy to use xwiki behind Apache reverse proxy (for https ) on same server with xwiki 8.4.4/Tomcat 8.5.11 and probably another reverse reverse proxy (that I can not administer).

Very often I can not open pages with CKEditor, I have this error (displayed by FireBug)

Error: Load timeout for modules: ckeditor
Line 7

I have not this error in Chrome anyway on same PC but I want to debug this.
My FF can load CKEditor on

By the way my users use firefox on Win7 and have some lagging problem sometime during CKEditor loading…

Do you have some way to debug this?


Pascal B