Hey guys, DSP will always (for the foreseeable) be an issue at some point. So, you are always balancing between ultra efficient Plugin choices vs best sound (never a good start!) or bouncing/freezing. I find slate to be very good on sound and on DSP and it is the MMWA weapon of choice too for individual channel console and musical eq and compression. Fabfilter proC2 and ProQ don't seem bad on DSP either for technical eq and compression. Also on the MMWA recommended list. This isn't without good reason. I think ProL may not be as good in DSP but need to test that more. I am using all the fabfilter with lookagead and 4x oversampling where available.
Even if you keep throwing money at faster and faster CPU's and RAM there is often other issues that mean these new 'speeds and cores' are not used fully, so I won't open that can of worms up. Google this and you will find lots of checks and tweaks so that you at least know you have the maximum 'realtime' DSP at your disposal to begin.
So, then it will come down to workflow. Before I started the course, I wanted to keep all my VST synths running from their instrument channel. This means the same DSP that I want for processing the channel is already being hogged by the synths that need to turn the 'midi' input into the 'audio' output for the channel. By committing the tracks to audio (bounce in place), even if keeping the midi and disabling the original midi track, you will release more of that valuable DSP for the job in hand. Hope that bit makes sense? The point of keeping the midi/instrument track is just in case you do want to go back!!
As for the orchestra, I am not onto advanced reverb yet(!) but if you have a larger 'space' say large hall and put a lot of the level on the send from you instrument, it will be distant. If you had a small space 'plate' or 'small hall', and sent less level of send, that would be closer. So using the suggested 3 'sizes' of space and blending the level of sends according to your predefined place for the specific instrument will keep them in the same 'environment' and create the various 'distance' that you need. Again hope it helps and definitely go back over the course material as it is dynamite. Oh, and this won't kill the DSP as much as you think. Again, it is often everything else you are asking the system to do and then this just becomes the final straw...