I tried deactivating the Yoast breadcrumbs plug-in but it doesn’t improve the speed: still very long publish/edit process.
No, sorry. I haven’t tried yet to disable the plug-ins to find which causes trouble so for now we still go with the slow publish process.
Ok, thank you NitroMax!
Yes, even emptying the W3 Total Cache doesn’t help.
Which plugin was the culprit for you?