Ideas for creating a "Opera shared start page" feature

[Long Le]

I have just used Opera and found out that their New Tab Page load is incredibly fast. After searching, I can only know this feature was called "Shared Start Page". The feature improve loading time of their start page by sharing single webcontents. 

In details, I can only know that they created a render process for start page first at startup, then whenever a new tab page is opened, they only have to share the loaded webcontents to that new tab. 

Searching across Chromium codebase,  I still cannot figure out how they can "share" that singleton. Therefore I don't know where to start my experiment.

Is there any idea for this feature, I think that this is an interesting feature.