Erlang is throttling CPU?

connections
n1ql
server

#1

i have 3 node cluster of couchbase . few days eariler…all of sudden my erlang process is throttling my cpu (even i have 16 GB with 16 CPU).All the three nodes have same services(data,indexes and query).
server is Version: 4.0.0-4051 Community Edition (build-4051)
this is image of node1 only …if you want i will add node2 and 3 imges also.
can anyone suggest me …how i can optimize my couchbase cluster.