Design Studio with BW only?

I'm trying to build a demo using Design Studio to replace a web query built with BEx Web Application Designer.

I'm using the Design Studio client (SP02), but it doesn't work properly.

I can connect to the BW server (7.3 SP5) and see the query, assign it to a datasource and a crosstab.

The designer doesn't render the crosstab preview (it hangs on the waiting cursor), however if I execute locally the query I can see the tab and the data on my browser (IE10).

In the browser it's not very stable, scrolling the tab will the 'waiting' icon will come up and freeze everything.

It's a just a demo query, not many records in the cube.

Do I need a BO server to execute a query with Design Studio?

At the moment is running only on BW.

I'm just trying to understand what could be wrong.