Why retrieves a native app data faster than one with PhoneGap?

Question

I know that an app developed with PhoneGap is slower than a native one because at PhoneGap the whole code must be interpreted at runtime into a native one.

But could someone explain or has a good in-depth website which explains why a native app retrieves data (a picture or text) from a web ressource faster than an app with PhoneGap? Do both apps handle internet connections in another way, or is there more data retrieved by an PhoneGap app?