Just did a test in the ST app, response less than a second.
I was having issues a few days ago. It was unresponsive and I couldn’t connect to the Hue hub (with the Hue app). Rebooted the hub and updated the firmware.
My Hue system seems to have completely melted down this morning. It can’t reach any of the bulbs. All the firmware is up to date and it has been rock solid for years (can’t remember the last time I had a problem with Hue bridge itself).