I have around 125 devices on a v3 hub. I’m not sure how much load each device adds versus extra drivers, or whether the efficiency of the driver matters much.
On FW 44.x, my hub was completely unstable with 29 running drivers, going into that failure state 2+ times per day. I reduced to between 19 and 23 and it was stable.
I’m on the firmware beta, and FW 45.x adds an attempt to proactively free up memory by restarting drivers when memory in use exceeds some threshold. This is only visible in logcat, but could lead to timer resets or missed events. With 17+ drivers I saw this happening routinely. I currently have 16 running and seem to be stable, but will likely reduce further for breathing room.
So there are definitely limits to what the v3 can handle. I haven’t seen any official public guidance from ST though so it’s all guesswork to figure out when you’ve crossed the line. The v2 hub has twice the memory, and from what I’ve seen others post may actually be able to handle 50 running drivers.
Remove some drivers, consolidating where you can to have a single driver run more devices. Buy another hub and distribute load between them (I’m not crazy about this idea - both the v2 and v3 are getting to be old models).