Thanks all for the replies so far.
Thanks, Mark. Yes, I use FX on the buses, also. What I typically was doing was FX on each of the tracks, then on the bus, and eventually on the master (EQ and Compression used on just about everything, then add reverb/delay and/or modulation as needed). As I started working with some of the more complex mixes (L/R, Samples, Rooms, OH, etc) that have close to 100 tracks, my system starts to get a little laggy (it's a 2012 macbook air, somewhat expected).
I was looking at ways to decrease the DPS and FX Sends (mentioned in many of Warren's mixes) seemed to be a way to route multiple tracks through a single FX and reduce the amount of processing needed.
At some point, I'll upgrade my system and I know I won't have to worry about this at all - but was looking for how people were leveraging the sends in their mixes. Good stuff. Would be good to hear from others also. I never thought of putting FX send for compression as I typically would use a 100% wet mix on a send, and where compressors sometimes give the capabilities of wet/dry that I love, I stay away from it. I'll look at the Parallel Compression for drums and see if I can leverage it there (I know it can be done - just not sure I can do it effectively...lol).
Part of the fun is experimenting with the suggestions...