Audio and Video Transitions making file size too big

[n0n0]

I've realized that the addition of Audio and Video Transitions have drastically increased my project file size (typically to 12MB), slowing Premiere to a halt. 

I've stopped using Morph Cuts altogether, largely because of this, but still need to use Crossfade for my audio.

I'm working with a project file that is approximately 1MB.  The project is about 90 minutes of interview footage, so I use approximately 180 Crossfade transitions for the whole project.  

How can I add those audio transitions without it increasing the project file size so much?

Or is there something I could be doing better?

[Ann Bens]

You cannot exclude transitions from the project file.

On a side note 12 mb you can hardly call huge.

Crossfade should not slow you down.

This interview footage is it of variable framerate?