Is it possible to know how much the HUB or MESH is loaded, like in regular pc “task manger”?
Any tool to manage load?
I did change the reporting intervals for lot of devices and meantime have no problem, but as many of us the quantity of devices are growing.
Does adding second HUB will help to manage load?
Mesh networks don’t work that way because they are not continuous connections. By design, the messages are tiny and hopefully infrequent.
There are tools which will show you the message routing, but unfortunately smartthings doesn’t provide any of them. Some community members have bought an additional device and then used the tools that are provided with it, but most people won’t have to do that.
Z wave is a very robust topology. About the only two things you can do to mess it up are:
One) don’t have enough repeaters or
Two) add software that does a lot of polling.
But other than that, up to about 150 devices, you should be fine. There’s a hard maximum at 231 (Plus one for the hub), but you may start to see some slowing down above 150.
See the following FAQ (this is a clickable link). Start with post 11, then go back up to the top of the thread and read the whole thing.
As far as adding a second hub, smartthings does not allow you to add a second hub to the same location, so that’s not going to help. 
@JDRoberts Thank You!
Just having strange issue: all my devices are Z-wave plus plus few Zigbee, all connected well and not far from each other, specially in a backyard I have 3 robust GE and Inovelli outlets.
While adding new Zwave - Im doing it close to hub than taking it to designated spot and trying to rebuild Z-wave to create new routes. And looking on the repair log
For past few days nothing happens there for VERY long period of time.
Rebooting everything (router and HUB), running again and it takes around 10-15 minutes to start to see first log.
I have around 60 devices in total meantime.
There have been some reports recently of problems with the Z wave repair utility itself, but just in the last week or two. So I would suspect that I think. You can definitely report it to support.