if on/off optimization is enabled, try disabling it--or vice versa (the former will cause problems if a device doesn't accurately report its state back to Hubitat, which itself could be a problem, but...)
if they are Zigbee bulbs, consider turning on "Enable Zigbee group broadcasting," which will cut down on the number of commands sent over your network (you can still turn this option on if there is a mix of device types or no Zigbee at all; it will just ignore the devices that aren't Zigbee, so there's no point in the latter case)
try using the new-ish "metering" option; I think I've seen staff suggest values of around 75 to start, though higher certainly wouldn't hurt (will mostly matter if you're not using group broadcasting). This spaces out the commands a bit and may help if network saturation causes the problems you're seeing.
Finally, what kind of devices are these? If they are Zigbee bulbs, what does the rest of your network look like (what kind of devices)? Many Zigbee bulbs have been known to be problematic when mixed with non-bulb devices.
