Need advice on mixing down stems to conserve CPU power.

   I have a pretty good PC, built by ADK and forgive my I don't recall all of the specs off hand.  I am running windows 7 64 bit,  i3, I believe it's 3.07ghz?  if memory serves...  and I upgraded the ram to 16 gb, Just a month or so ago I upgraded the graphics card rather than the one on main board of the PC.
 
  My mixes are getting more and more complex as my skills improve and I want to control things better.  Typically a mix for me is something like 13-14 mic's on the kit including cymbals and room mics.
 2 tracks for bass, with a DI.
4-8 guitar tracks (with cleans,dirty,harmony parts, leads etc.)
3-4 vocal tracks.
Maybe synths/keys, maybe a tamborine.... who knows?
So 24-30 tracks,   end up paired down to 12-15 buses with fx busses, parrallel comps, etc.
 
Then I am doing increasingly more automation lately....  Really fine tuning the mix and riding faders mostly, some fx send manipulations written in too.  And I am now running out of power!   Today I had a mix similar to the above going and I noticed the CPU meter in sonar getting up there as I continued working.  At about 55% I started getting a few glitches, audio pops, etc. here and there.  I started saving like every 2 minutes...
at 59% I was just about done, I was listening back and decided to add a long delay to a bus and send the vocal to it at the end of a few lines to get the echo effect vibe in the choruses.   I set up the bus, set up a send from the vocal to it,  opened the plugin to tweak it and after about a minute sonar froze up (screen grey but was still playing back).   Had to force close it.  Reopened and re-added the bus, effect again (I was so close to dune I was hoping to get lucky and finish it up without further issues)   Decided to go with a sonitus delay (rather than 3rd party plug) this time to save power.  Went to write automation and it WON"T LET ME.   I mean, I can go through the motions... but it's not writing anything.   I think I am just SIMPLY out of processing power. ?
So I am contemplating mixing down for instance my bass tracks (One DI, one Sans amp) processed separately, both to a bus, comped and eq'd together.  If I mix that all down to one bass track (with all the eq, FX, and automation baked in) I can turn all that stuff off and save power that way right?    Repeat for guitars... 4 rhythm tracks (2 parts) all dumped to one stereo track etc.
 
Does this make sense to you guys?  Have you run into this before?   IF so, what is the best way to deal with it?  Eventually I will have to upgrade to a better computer again... It has been a few years now (8 years I think).   Any help is really appreciated.

I agree with Greg.  Try freezing the synths first, stems will really restrict you when it's time to mix.

dcumpian
You cannot freeze a bus, so that isn't an option for tracks routed to a bus and then processing the sum.

 
No, but you can bounce the bus to a track and archive the tracks that feed the bus.
 
It should also be noted that running out of CPU will not normally cause stability problems in, just crackles and pops and eventually an audio engine dropout. If SONAR is freezing or crashing under heavy load, something else is going on.
 
Also the OP didn't mention ASIO buffer size. Increasing this to 1024 or more would be the first step to ease CPU load if the project is at the mixing stage and no more tracking is being done that requires low-latency input monitoring.

It might be nice exploring stem cell research anyway
But seriously, I mixed stems as merely an experiment a few years back (trying to add depth)
it WAS different than single track mixing, that's for sure.
I noticed FX stood out more up front and center in the mixes (Delay, Reverb, Exc).
 
When you begin to use light compression on a smaller group of instruments it begins to glue them together.
Much like the counter part of track mixing.
 
I think a work around is definitely in order, but don't rule out stem mixing all together.
I learned a lot about mixing and mastering while researching stems.
I hope you do as well. Good luck Chuck.

chuckebaby
It might be nice exploring stem cell research anyway
But seriously, I mixed stems as merely an experiment a few years back (trying to add depth)
it WAS different than single track mixing, that's for sure.
I noticed FX stood out more up front and center in the mixes (Delay, Reverb, Exc).
 
When you begin to use light compression on a smaller group of instruments it begins to glue them together.
Much like the counter part of track mixing.
 
I think a work around is definitely in order, but don't rule out stem mixing all together.
I learned a lot about mixing and mastering while researching stems.
I hope you do as well. Good luck Chuck.

this brings up a somewhat off topic, but related question that I have.
 
When I mix....  Im kind of mixing stems anyhow even if I dont print everything to stems.
 
like...  all my guitars are routed to a guitar buss within sonar.  Once the balance from one guitar to the next is set, and any individual track effects are set....they all go to that guitar bus, and all I have to do is mix all the guitars collectively by using the guitar buss.  Just to stay on topic, once those fx and balances seem good...as I said I freeze the individual tracks.  That saves me a ton of CPU.  at that point my only 'live' plugins are on the busses.
 
end result is usually a bass, guitars, drums, vox buss for a basic arrangement.
 
in effect I have 4 stems to mix even though all the individual tracks arent truly mixed down.
 
So here is what I am ultimately getting to.  did you ever notice a difference in how the program responds when you experimented with actual stems?
 
Each of my busses will always have a light compression to glue each instrument together.  and maybe an eq on each buss to shape that whole group of instruments a bit. 
 
im wondering if say 6 guitars bussed to one track, and light eq and comp applied to the buss "acts" the same as the 6 guitars mixed down into a real stem, and then that one singular track getting processed with the same eq and compression that I would have used in the buss.
 
it would be an interesting test just to see if any program limitations cause any differences.

Greg, I agree with Brundlefly.  I can't imagine that there would be any difference at all,  is the same thing. A summing of all tracks and FX going to that bus.