there is no easy Answer, as it depends on alot of things.
format of video using, export settings, HD or SD, Effects, Layers. All these things can slow down an export.
Sorry, in re-reading my original post perhaps I wasn't the clearest.
What type of video that is brought into premiere from a external source, such as AFX, will render/export the fastest from premiere?
Not a video that has effects done inside of premiere, but one that is simply brought in, used with other clips inside premiere, then exported out.
Looking for what codecs render faster on movies that are brought into premiere.
I would suggest one that matches your Project setting requires less processing than one that does not match.
eg if your project is NTSC DV...output the same from AEFX. Same would go for a 720p ,1080, 2k project or anything else.
Does premiere have a preference for 'native file formats'? What are the native file formats, and does that mean it does not have to render them?
Your Project setting is usually "native". eg P2 mxf, HDV, DV etc... f it matches your source.
ie. match your project to your source and then you are basically "native"
If you import a file of the same type...you are native.
Rendering depends on hardware, effects etc....
CS5 and MPE now provides a realtime edit experience in the timeline without rendering previews (for many fx.)
All exports to a final movie require "Rendering". The speed of that depends on the hardware and effects etc but the quickest is usually if you are rendering a movie that matches your Project.
BTW: you need to think about what the final use of the movie is. That determines what you will export. It may not be the fastest.