Okay, here’s some quick feedback…
On my Mac Book Pro (Retina, Mid 2012, 2.6GHz i7, Intel HD Graphics 4000), macOS 10.13.4, I can’t see any significant difference in terms of CPU load between CViewContainers or CLayeredViewContainers. Which kind of corresponds to what Arne is saying. It’s only when I pass an additional kNoCALayer to my CFrame’s open function like this, that things become slightly worse:
#include "../frameworks/vst3sdk/vstgui4/vstgui/lib/platform/platform_macos.h"
...
CocoaFrameConfig config;
config.flags = VSTGUI::CocoaFrameConfig::kNoCALayer ;
if(frame && frame->open(parent, type, &config))
{
...
}
Which is essentially identical to commenting out the “[nsView setWantsLayer: YES];” portion in nsviewframe.
So it’s actually the other way around in my case. However, this was just a quick test session using a single F-59 instance in REAPER64 and macOS’ built-in activity monitor to measure CPU load.
You already mentioned that it may be restricted to a certain setup / host environment, though.
Maybe it’s something specific your plugins’ code? I don’t recall the BX code too well, but iirc meters were polled and updated in your editor’s idle(). What if you remove that for a try?
Since you can reproduce the issue easily on your machine, can you maybe try installing the Fuse Audio Labs F-59 which has a slightly bigger GUI and see whether it also slows down your host as described?
Best,
Reimund