I had only run Diva on my studio machines which are very similar to RickRepsher's (racks, 64 gig, SSD etc) and hadn't really given Diva a bash on the old Lenovo T410.
Just running ASIO4All on the internal sound card at 128, with jbridge hosting Diva, performance mode on (doubling the latency to a reasonable 256) 4 note polyphony is hitting is hitting a max of 60%, averaging 40%.
That's pretty ouch but OK.... it's still well playable.
I flipped on Diva's multicore support. The Cantabile meter dropped to an average of 15- 20%. There is an occasional spike which can probably be tracked down - and of course it's patch dependent, exactly as it is with Omnisphere.
From here on I have had to rewrite everything I thought I was going to say.
Diva was reasonably under control. It was the only plugin instantiated in C3.
I flipped 2C's Breeze reverb into the picture. None of 2C's stuff is light on the CPU. Breeze has been a good live solution, especially when bridged in performance mode (who cares about a few ms of predelay on a reverb?) As soon as it was switched in, C3 went into overload with regular +100% peaks. Turn off Diva and run a Synth1 into Breeze and we're back at a non-peaky max of 16%.
Turned off multicore in Diva. C3 Load drops back to a non peaky sub 40% load with Breeze running.
These things interact differently, and there is voodoo involved.