I run my Home Assistant OS as a VM under Proxmox and when I use the Ember driver everything works fine, but the overall cpu usage of the VM is 2% of a N100 cpu with 2 cpu cores assigned.
When I use the ezsp driver the overall cpu usage on the exact same setup is 0.5%.
Is it maybe better to just stick to the ezsp driver for now?
Thanks to everyone contributing to this topic! I was able to successfully update SkyConnect and change to ember without having to re-pair any device.
I have very similar setup (Proxmox) and i’m facing same issue. After switch to Ember my average CPU usage grown from 0.15% to 1%.
thanks for this dumbed down version. it can be this easy 
FYI, the latest ember driver for Z2M now has experimental support for EmberZNet 8.0.x.x firmware (where EZSP protocol version incremented to EZSP v14 and it is built from Simplicity SDK (not Gecko SDK):
https://github.com/Koenkk/zigbee2mqtt/discussions/23224
Nerivec does provide some experimental EmberZNet 8.0.1.0 firmware builds (flashh them at own risk):
puddly also built experimental EmberZNet 8.0.0.0 firmware for Home Assistant SkyConnect / ZBT-1:
Again, there are no new features or functions in that the new EmberZNet 8.0.0 firmware release brings that Zigbee2MQTT’s ember adapter driver has been made to take advantage of, or at least not yet.
PS: Nerivec suggests using his ember-zli for flashing (which in turn depends on the latest zigbee-herdsman):