Very slow ajax loading times?

Hi,

I am using this to host some menus on my site. (menus meansing restaurant menus, not navigational).

I have the following setup:
Node Fields
-Field collection: menu
-menu description
--Field collection: category
--category description
---Field collection: item
---item name
---description
---image
---price
---attributes

so yeah, three levels of field collections. My problem is that when I am trying to add more items, or add categories, its often very slow. It has only been happening as I have been populating my node (my first one which I am testing as I build the site at present). and has only been happening once i have had a fair few items in. I am putting the data from a real menu in however, so this is a real use case. Im not trying to overload it with data i would never need etc.

When I press "add another" to add a new item or category (or a new menu but I havent done that yet), sometimes its taking up to a minute to load. The blue ajax spinner and "please wait." appear immediately, but after maybe 5 seconds it stops spinning and firefox freezes. I cannot do anything until up to a minute later after it has finished.

Should I be using a different module for my purposes? Or is there a way to fix this? would it matter that I am using shared hosting at present? What aspect of upgrading my hosting would improve this speed?