Gain Stage Strategy Sanity check

I'm looking for a sanity check on an approach to gain staging... 
 
So... I've got a rough mix of a drum performance (via Addictive Drums) and am now building a rock tune around them. The track meter levels are healthy. Nothing clipping. Sounding pretty good. Of course, when summed to a drum bus, collectively, it's too hot and I want to leave headroom on the master fader to add in all the other instruments. So, I want to reduce track levels, so when they collectively hit the drum buss, it peaks at something workable(say, -12 db).
 
So I want to knock 10 dB off each of 10 drum tracks (the kit pieces) as the first insert on the individual tracks, and see where that gets me on the drum bus meter. I put the Hornet VU Meter Mk3 -- which allows you to group all the tracks together and knock the 10 dB off with one click. Fast. Nice. But now I've got 10 instances of the plugin running, leaning on my CPU.
 
Instead of running 10 instances, can't I just put ONE instance of the plugin on the drum bus to knock the summed output of the kit down to my target of -12 dB? Am I missing something here? Any reason not to go this route? 
 
Thanks for any advice. This community is incredibly generous... really stoked that a new hope is dawning with new ownership... 
 

I'd second that - just temporarily group the tracks (select and press ctrl) and bring down the volume faders.

Alot depends on whether you're using AD's built in mixer to add processing or create a balance but if all that's being done in Sonar then dropping the track faders is the easiest way to do things. And sends routed to e.g. reverbs or delays might need adjusting as well to keep the original sound.

Or just drop the input gain on the bus they're routed to as you suggest.

Keeping some spare headroom in the tracks themselves is always a good idea in case you find you need to re-balance the kit later on so if any are nearly peaking dropping the gain at the track inputs, or at least pre-fader, might be a better way to go.

An easy and low overhead method is to insert an empty effects chain into the pro channel. Then use the chain's built in gain controls to do the reduction. Lowering the rotary gain controls on the tracks will also adjust the volume. Both these methods will affect any compressors after where the reduction is applied of course.

Me, I'd most probably either lower the aux bus volume, drop the track faders or even freeze or bounce all the drum tracks individually then set the bounces up as a new mix and archive the original tracks (or delete them then save the project under a new name) to make sure I had the originals if I need them.

I guess it depends on whether you are using sends from the drum bus to an effects bus, or just using insert's on the drum bus. If you're not using sends, the trim knob is the easiest way if you're individual tracks aren't too hot.

Yes Offset mode will offset the the volume envelopes (keeping your automation moves in check) as opposed to adjusting trim (gain) or channel faders. Adjusting the trim will change the input to your plugins and you wouldn't want to disrupt your perfect amount of gain reduction on your favorite compressor. (unless something was recorded too soft and actually needed more gain before it gets to your plugs) And Yes you can quick group any or all of the tracks, hit 'O' (offset mode shows a + sign by the volume and pan to let you know when you're in it) hold control while lowering or raising the volume slider and All tracks quick grouped will offset the same. Again use the quick group manager (right click the volume slider) to set how the quick group reacts when raising or lowering (Absolute, relative, custom, preserve mix) It's REALLY handy for setting that final Lead vocal level without affecting Volume automation, or compression. You can Offset aux sends too, keeping your aux envelopes in check while changing their overall gain. Love Offset mode!