I have a MongoDB cluster. The cluster is currently writing (mostly inserts) 4k/sec. When I increase the number of inserts from 4k to 5k, I can see oplog window slowly reducing, possibly to 0 if I do not intervene. What are ways I can increase the number of inserts while maintaining oplog window? The cluster is on AWS m5.2xlarge, CPU is running fine (under 20%). Would a more performant instance help in this regard?