A couple of weeks ago I have been experiencing high CPU usage in my GNS3 home lab. After some trial and error, I localized the issue and discovered that the cloud device connection is the cause.
My old topology
I have a cloud device connected to a hub. The hub connects to the HQ router and the Unified Border Element. At some points in time, I hear the laptop fan working hard. This was not like that before adding the Unified Border Element. I think if you add more than two devices to a hub, your CPU will suffer.
So my old trick for this high CPU usage was to disconnect and re-connect the cloud device to the hub. However, one time out of three I get the gns3 waiting for http://127.0.0.1:8000 error. And my GNS3 setup crashes.
My new topology
I was thinking of getting rid of hubs. I tried a switch. But it did not establish cconnectivity between connected devices despite they were on the same vlan (GNS3 bug?)
Then I thought about putting a multilayer switch and doing the right routing configuration to make things work. So I had to segment the network into three subnets and route between them.
It did the job.