Stuttering with VST3 using Cubase


I am a developer for Kush Audio, we are having some difficulties porting the Omega plugins to VST3. When running these in Cubase there is a massive stutter to the point of being unplayable (as if the playback is constantly starting/stopping multiple times a second). This only happens with Steinberg products though, on Reaper and Bitwig with VST3 this is not the case.

I was wondering if anyone had any insight into this matter and knew of a possible solution.
Any help would be greatly appreciated!



  • which version of Cubase do you use?
  • check if your implementation of IAudioProcessor::setProcessing () it should respect this:

/** Informs the plug-in about the processing state. This will be called before any process calls
start with true and after with false.
Note that setProcessing (false) may be called after setProcessing (true) without any process
Note this function could be called in the UI or in Processing Thread, thats why the plug-in
should only light operation (no memory allocation or big setup reconfiguration),
this could be used to reset some buffers (like Delay line or Reverb).
The host has to be sure that it is called only when the plug-in is enable (setActive (true)
was called). */

  • did you try to create a lighter version of your plugin by disabling some internal functionalities? in order to isolate the problem.


Hi Yvan,

Thanks for the reply!

This seems to happen on multiple versions of Cubase. We haven’t actually implemented our own VST3 interfacing (we are using JUCE, perhaps this is the root cause?). I am in the process of stripping away some plugin functionality to try and isolate the issue as it seems specific to only a few plugins.

I will update on the findings.

Thanks again,

So it seems this is due to using JUCEs updateHostDisplay() function. This is for a plugin where a certain parameter range changes when a specific button is pressed. The function works fine for VST2 and VST3 (for other DAWs) but with VST3 (only on Steinberg products) it causes a massive lag/stutter unless updateHostDisplay() is removed from the code.