we want to hide the FM menubar in Webdirect. For this purpose we created a completely empty layout to which we switch via file options and the very first script step in the start script hides the menu.
But still hiding this menu takes a while so that the user sees it.
I struggled with this for a while too and never found a way around it. It seems to be directly related to your server's performance, as I've seen some servers that run the open action fast enough that you do not see the bar ever appear.