Ok, bearing in mind this is Win10/Cubase Pro 9.5.
I loaded a fairly recent project. At it's busiest section there are, all playing at the same time:
4 vocal parts (EW Choirs)
3 Brass parts (EW Brass)
2 organs (HALion)
Drums (GrooveAgent 4)
These all go through 14 groups, all with their fair share of PA plugins.
I set the buffer size to 64 samples, ASIO Guard to High. The Audio Performance meter was at around 75%, cpu around 50%.
There are 40-odd PA plugins throughout the track, including Opto, Vertigo compressor, Millenia EQ, BX 2098, Acme XLA-3, Vertigo VSM-3, elysia alpha, XL2 and Dangerous Bax. There's also a bunch of Waves TG12345 and REDD scattered about. 5 instances of Satin and 6(!) instances of Valhalla VintageVerb.
The track plays with no glitching.
If I set ASIO Guard to Normal, there is some glitching when all the instruments come in at the same time. The Performance meter and the disk load meter both leap into the red zone.
However, if I disable all the Waves plugins (the Abbey Road stuff is quite cpu heavy), there are no glitches (at 64 samples, and ASIO Guard Normal) at any time.
The cpu is an i7 4790 from 5 years ago, running through a RME AIO interface, 16 gigs of RAM.
I should add that none of the plugins is being pushed hard, the effect is cumulative.
This is the track. Plug plug! The big finish is around the the 6:00 mark.
https://soundcloud.com/googly-smythe/19 ... volume-two