Hello again, it will become a little difficult. The tool is called Instruments but it is not preinstalled. It is part of Xcode, the app that developers use to write and compile code. You can download Xcode from Apple (Xcode on the Mac App Store) for free, but it is quite huge. Once you have installed it, you should be able to invoke Instruments via Spotlight search.
You run Dorico and Instruments in parallel. So you prepare Dorico for playback, then flip to Instruments and start a System Trace and hit the record button. Then start playback in Dorico and let it drop out.
The data that Instruments gathers can get pretty big, therefore record in Instruments - if possible - only shortly before the drop outs appear and only a few seconds into the drop outs.
If the data size exceeds the limit you can attach here, please use a file sharing service like for example DropBox.
Should you need more detailed help, please write mail to ‘u dot stoermer at steinberg dot de’.