This summary provides an overview of the consistency and performance trade-offs in MongoDB and Couchbase Server. In MongoDB, data is consistent but read performance can be limited due to asynchronous replication by default, while synchronous replication improves write performance at the cost of reduced read performance. In contrast, Couchbase Server consistently delivers high read and write performance across all nodes, thanks to its partitioning and replication strategy where every node acts as both a primary and secondary node, allowing for efficient distribution of write operations. While MongoDB requires more nodes to achieve similar performance, Couchbase Server's approach enables it to execute more writes per node, leveraging the full potential of its cluster.