Multiple instances but not sharing load

We are running 2 instances of camunda 7.8 on aws, and at times when processing many many process instances, we find one camunda instance at 100% cpu for hours while the other is practically idle

Is it possible to spread the load evenly amongst all available instances ?

It could be that the default job executor settings don’t suit your throughput.
I’d suggest changing them and seeing if that improve things.
You can read more about it in the docs.