Fatal Error when saving menu

Hi! Thanks for a great theme and awesome support. But now i really need some help.

I’ve some serious problem when saving our menu. It takes up to 5 minutes to update the menu and it’s impossible to work until it’s finished and give me an error. (Not in default Language, just seconday languages).

Fatal Error: Allowed Memory size of 268435456 bytes exhausted (tried to allocate 56 bytes).

I’ve set 512M in the configfile, still the same problem.

Thanks