This is why that page is taking so long to load. There isn't anything this plugin or any other plugin can do to help that, you'd need to talk with the developer of this module to see if he can make it perform better or you'd need to use another extension to achieve what you want."
First thing it is I'm on development stage to load placemarks dynamically, ie by AJAX requests. I hope I'll find time to do it in this month.
As for optimization plugin and etc, in component options you can set "Load delay" to your value, in this case map initialization call will be with your delay in milliseconds
I think main delay can be caused by many placemarks, because it gives page source size. When I implement dynamic loading placemarks - it will not have any page source addition, because it will be.called after page loading.