So I have a recommendation based on findings with the ST team. I recommend that the number of selected devices in a single webCoRE instance does not exceed 50.
At 81 devices, the start time for the piston is around 300-500ms. At 127, it goes up to 1500-2000ms.
So breaking them down by area of expertise (ie lights control in one instance, music control in another, etc) may improve performance.
Also, don’t just select all devices because you can, try and select those you need only.
I will provide a way to identify devices that are selected but not used.