Saving resources: Track, Mono or Stereo

I have a few mono tracks that need stereo imaging.
 
Would it be more efficient make a copy of the track and use two tracks for Stereo (two buss)?
Or
Create a Aux track for say left or right track, then to two buss?
Or
Bounce mono to stereo and  split at the Aux or buss stage?
 
From a  resource point of view?
 
Other ideas?
 
Thanks!

You can use the Freeze Track feature and get the best of both worlds.  Take a mono track w/ Stereo Interleave enabled and then add your stereo imager plug-in.  When you have it sounding how you want it, hit Freeze and SONAR renders it down to the stereo waveform and writes this out to disk just as if you had down all that manually.  This will save plug-in resources with any plug-in -- not just the stereo imaging example.  You will find with some plug-ins that they are very resource intensive and so Freeze makes sense and you might find with others that they are pretty light weight and not worth the hassle of freezing/unfreezing.  
 

Any advice would be irrelevant without knowing what kind of stereo processing you intend to do. Do you have a plugin that doesn't work properly with a mono input? Do you need to process left and right channels independently? Or do you just want to add a basic stereo effect such as chorus or ping-pong delay to your mono track?

a mono track, duplicated and panned left, right.....
nope.
 
to stereo image mono tracks,
you'll have to use a send from each mono track and send it to a stereo effect,
that takes each mono tracks and does something to it that creates a stereo effect (say, a doubler, or stereo delay)
 
be careful of phase issues.