Very long audio render preview times

Hi,

So I have a 3x50min interview videos all with the same settings. 

I've duplicated them multiple times and nested them as each video has some different graphics or there might be 2 different people on screen at once. Below is an example of what I mean:

- Interviewer (Fullscreen)

- Interviewer (In a graphic skin)

- Interviewer and Interviewee 

etc

I've then put them into a multicam sequence so I can switch between them easily.

When I render the audio it takes forever! NOW I'm sure is me but what am I doing wrong?

Also I went into each nest and deleted the audio to see if that would help and it still takes forever to render just the audio when there is nothing in there. Thoughts?