CPU utilization increased after upgrade from 2.5.1 to 3.1.0

Hi guys!
We’ve upgraded our Couchbase cluster from 2.5.1 version to 3.1.0 and found that CPU utilization increased from approximately 20% to 50%. Is this a common problem for version 3.1.0?

for clarity, the graph CPU from one machine before/after upgrade to 3.1.0
We use 3 clusters with bi-directional xdcr between