How to debug which VSTs are using CPU / RAM?


(Note, I’m on Mac Monterey using M1 chip running Dorico in native mode.)

I’ve seen many posts about overall Dorico CPU usage. I’m finding that Dorico mostly does fine, but sometimes, the VSTAudioEngine spikes up. My projects are pretty heavy on VSTs, so I don’t necessarily think this is a Dorico issue.

That said, I would like to understand better what is using what. Does Dorico (or VST in general) offer any tools to see which VSTs are using how much CPU / RAM?


As you know, Dorico consists of two processes, Dorico itself and the VSTAudioEngine which hosts the mixer and the VST plug-ins. Since plug-ins get loaded into the hosting process, they become a part of that process and therefore you can’t distinguish easily any more what uses how much RAM or CPU because it is all mixed up.
Some plug-ins themselves give in their UI an indication of how much CPU or RAM they use, but that’s not the general case.
So you can only guess by comparing. So e.g. load a certain setup and look in Activity Monitor. Then add a plug-in and see how the memory or CPU load changes. Pretty clumsy but…

Got it, makes sense, thanks!

If you use Vienna Ensemble Pro to host all the VSTs instead of Dorico, it will display the CPU usage for each instance. For example when I was playing back this brass section in Dorico, VEP reported my Samplemodeling Trumpet and Trombone VSTs were using 26.4%.

With just the sound loaded and nothing playing in Dorico it’s around 6-7%.

On Mac, I have used iStat Menus for several years. This puts a lot of critical information right in the menu bar, including memory and CPU usage.

This is really handy because you can see memory change as your are adding new instruments. For example, I can instantly see that the memory usage on my M1 goes to 90% with Dorico and the NI Cremona Quartet loaded.

iStat Menus, iStat Menus, is not a free program, but once you use it, you may become addicted to knowing what is going on inside the little black box.