Hello,

this issue is not directly related to the Responsivizer template.
It's due to a slow javascript rendering of pages on your website, you have a lot of scripts that slow down the browser page loading and scripts engine rendering. Probably the Google Translate module is mostly responsible to slow down the scripting engine. As a consequence the top menu take a while to collapse.

To minimize this side effect you can add a CSS rule like the following to the mobile template file main.css:

Code:

nav.top_menu ul.menu {display:none;}

In this way it will be hidden by default using CSS.