Vertical Multilevel Slideout Category Menu Loading problem

Hello,
I have installed Vertical Multilevel Slideout Category Menu addon in order to make category menu better accesible, but it is not working.
Shop has many categories and subcategories and hundreds of items. When page start loading it freezes for 2-3minutes in the moment when it is loading category menu and after some time it results in blank category menu. This all problem might be caused simply by too many records in my menu and script just cant load them all at the begining, but it should load ofter some time. If anyone had same problem please help me.

Thanks for any response.