Version:           4.0 (using KDE Devel)
Installed from:    Compiled sources

here you can see the problem :
http://www.kde-look.org/content/show.php?content=51637

And in the Maxilys comment, it is said that the serenity theme solves this issue increasing the speed to display submenus to half a second.

It would be realy cool to have this donne, as it is in serenity.

One more thing:
it can be good to delay the "closing" of a submenu ( contextualy ? ) for instance, when you are in the konqueror configuration, toolbox, you may whant to add/remove more than one toolbox. know, you have to reopen the config,then go to tollbox, and choose whitch one to change. Moreover, I sometimes mis my target, and after the 4th cycle, I get realy bored.  -> Is it a bad design of the konqui toolbar ? I don't think so, just the menu should not disapear when clicking some of the elements. --> inconsistency ?? I don't think, because there is a litle sqare whith or whithout a tick, which show this is not an open_new_window or act_imediately thing.