Java SE (Java Platform, Standard Edition)

I have to create a bunch of rather heavy (in processing time) JPanels. In order not to block the EDT during the construction of these panels I was wondering what part of the construction/activation/usage HAS to be done on the EDT and what can be prepared in advance on a side thread?

For me construction means, the setLayout, setBorder- kind of stuff.
For me activation means the actual adding to the GUI (f.i. getContentPane.add).
For me usage means the actual filling with dynamic data (f.i. setText).

Thank you in advance.