Does anyone know if there is a way to force a new JavaScript thread for a new window?

I have an ExtJs application whose render steps are slaughtering user interaction. I can't toss the whole Ext application right now, so I've devised a way to make use of localStorage to manage passing events between browser windows and replacing a high activity data entry portion of the application with an Angular2 app spawned in a new window from the Ext app. 

While things are performing wonderfully on the Angular2 side of things, when the parent window with the Ext application hangs during a render step, the window with the Angular2 application hangs as well causing users to lose keystrokes (which is bad).

Ideally being able to divorce the Angular2 app's JavaScript thread from the Ext one is what I would like to do. 

Does anyone know if this is possible?