Zest at 350%?


I just noticed that when using Zynadsubfx my units temperature went up about 10C and top shows zest using 350% of the cpu when playing one note. It falls to 6% with no notes being played. Hadn’t noticed this before. Is this normal behavior?


Actually, with top -H it looks like the each of the 4 llvmpipe threads is using approx. 100% of the cpu but I’m in over my head here…

It depends on the patch/ preset you are using.

If you have the VNC option enabled, try to disable. The ZynAddSubFX native GUI is very CPU-hungry and you should only enable it when needed.
In fact, VNC should never be enabled unless you are using it, and certainly, i would never recommend having VNC enabled for true playing (reharsal or stage).


OK - Thanks. Now I see it was was graphics actions that were using so much CPU. I know this has been asked before but is there a way to still have the VNC-UI without incurring the VNC-engine graphics overhead? My Zynthian is physically remote so the VNC-UI really comes in handy but I really don’t need the GUI to the engines.

Best regards,

What do you use VNC for?

Hello Riban,

My Zynthian is located in a place that is difficult to access normally. I’ve got 6 hardware synths and it’s not easy to arrange them in my small space for physical access So all my actions that require access to the encoders and screen are done from my PC in combination with either Ableton or Midi-Ox to connect all the synths. If I want to do anything live with the Zynthian I can capture the necessary snapshots and turn VNC off. At the present time I am still learning all the amazing capabilities of the device and not anticipating going live anytime soon. The local synthesizer club meets weekly so I hope to do a Zynthian demo (DAW-less with a Keystep Pro as the only other control surface) sometime in the Spring.

Thanks for your support,

So you are using VNC to show the UI (mixer, control view, sequencer, etc.) but not the desktop (native GUIs, patchage, etc.)? This is a reasonable use case that we don’t care for. It is all or nothing with VNC. It sounds like someone should submit a feature request to be able to enable each VNC server separately.

I have long since desired the ability to separate engines’ core functionality from their GUI and only show the GUI on demand but that is a very challenging task, hence not (yet) implemented. Maybe one day…

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