How to asynchronously load a partial page in rails

In creating a ruby on rails / jquery app, there's a part of a page that is time-consuming to generate.

I want to change how the page is loaded so that most of the page loads right away, and a placeholder is reserved for the time-consuming part to load asynchronously, and be injected into the page with ajax / jquery when it is finished.

What I have now (simplified):

app/views/sample/show.html.erb:

<div id="theResult">
    <%= render :partial => 'calculate', :object => @org) %>
</div>

and the partial will use some parts @org to generate some content (hitting another external REST service).

app/views/sample/_calculate.html.erb

<%
    # code to take org and turn it into content
%>
<!--...html to display results here -->

I realize this is probably breaking proper MVC architecture rules since my partial seems to have too much logic, and would like to clean that up as well...

So I guess I have two questions in one: (1) how do I get this to work, and (2) how should I clean this up to follow good ruby/rails/mvc practices?