CB 5.1.1 select * from system:indexes taking too long

We are using CB 5.1.1 and we see that the query “select * from system:indexes” is creating considerable load on the system with an average return time of 33 seconds.

“users”: “couchbase”,
“statement”: “select * from system:indexes”,
“state”: “completed”,
“serviceTime”: “55.248812836s”,
“scanConsistency”: “unbounded”,
“elapsedTime”: “55.24885126s”,
“errorCount”: 0,
“phaseCounts”: {
“primaryScan”: 15,
“fetch”: 15
“phaseOperators”: {
“primaryScan”: 1,
“fetch”: 1,
“authorize”: 1
“requestId”: “xyz”,
“requestTime”: "xyz,
“resultCount”: 15,
“resultSize”: 3596

We will need some more info. Could you tell us the cluster makeup (OS, services enabled, how many nodes -etc), and also attach the logs ?
We can then take a look to see why there is a slowdown.