To control the speed of the menu and submenu items of jquery.mb.menu there are two params settable in the init function: fadeInTime, fadeOutTime. By default the fadeIn is set to 100 ms and the fadeout to 200 ms but they can be changed to merge your needs. Another paramm that influence the show and hide behavior is hoverIntent and submenuHoverIntent that define how long the mouse should stop over a voice before showing the menu or submeu; by default those two params are set to 0.