And I said back in post #10 that SONAR is sending the VST3 silence flags. It can be easily verified by using a test VST3. Please be patient while we try and investigate why this behavior occurs with Waves plugins. 

synho
Please find for me any  VSTi3 plug with audio inputs!

https://www.steinberg.net/en/company/technologies/vst3.html
 
In the first paragraph Steinberg includes virtual instruments under the heading "improved performance." I assume they did that for a reason, or do you think they're wrong and there is no improvement in performance with VSTi plug-ins and VST3?

VSTi plugins could have an audio input even in VST2 - there is nothing new there. Its just old wine in new bottles in this area.

So here is the reason why you see a difference in behavior. It has nothing to do with SONAR's VST3 implementation.
 
I asked Waves development about why there was a difference in behavior. The response I got was that they do not have any special implementation for the silence flags. This might be for technical reasons on their end but what this means is that the plugin does not take any special action on this state internally to bypass processing. Any change in behavior you are seeing in Cubase is definitely due to the host doing something internally. Presumably they are stopping plug-in processing in response to silence being sent for a long time. So as such this is not a VST3 feature at all but something specific to Cubase's implementation. 
 
I don't think we are likely to implement the Cubase like behavior since there are a ton of special case scenarios that would need to be handled to turn off processing and turn it on when audio resumes. As just one example delay compensation would be a can of worms there for us so it simply isn't worth the effort for us to do it host side. If a plugin wants CPU savings the vendor can bypass processing using the the silence flags as documented in the VST3 spec so if this is important to you please request the corresponding plugin vendor to implement it. As I mentioned earlier its not always feasible to implement such a feature depending on the internals of the DSP. For example even VST3 sample accurate automation is not implemented by most VST3 plugin vendors.
 
Please keep in mind that VST3 is a specification (like the MIDI specification) and not every feature needs to be implemented by a plugin vendor (or a host for that matter). A feature needs to be implemented by BOTH host and plugin for it to work. You can read more technical details about SONAR's VST3 implementation here.
 

A classic case of an incorrect conclusion based on reasonable logic.
 
A = B and B = C therefore A = C. The logic's fine, the flaw is the assumption that A,B and C are the only relevant variables.
 
Don't feel bad, synho. It happens to smart people all the time.

Noel Borthwick [Cakewalk]
I asked Waves development about why there was a difference in behavior. The response I got was that they do not have any special implementation for the silence flags.

Thanks, Noel for your investigation.
 
Here is reply from Waves on my ticket:
 
VTS3 Suspending is not supported with Waves Plugins. We currently do not have ETA on this fix. 
If you need further assistance feel free to contact us or visit http://www.waves.com/support

Best Regards,
Tomer Cherkasky
Waves Technical Support Staff
 
Seems Waves made just a VST3 wrapper which is not real VST3 with controller-processor module architecture. 
 

>>Seems Waves made just a VST3 wrapper which is not real VST3 with controller-processor module architecture. 
 
That is an over-simplification. Pretty much every major plugin manufacturer has their own internal cross platform framework which is a superset upon which they build multiple plugin implementations. That allows vendors to write a single plugin and publish it into multiple flavors, such as VST2, VST3, Audio Units, AAX etc.
 
Waves has a fairly rich VST3 implementation in some ways - they support the migration API, bypass and some other stuff. Most vendors don't support VST3 sample accurate automation and CPU savings. It would be nice to have a "VST implementation chart" similar to what MIDI hardware devices used to publish.

Thanks Noel, your insights (and technical chops!) are always appreciated.