XDCR in Couchbase Server 6.5 introduces a new feature allowing users to assign priorities to replication streams, with options of HIGH, MEDIUM, or LOW, to better manage resource allocation during data replication processes. This prioritization is especially beneficial when adding new clusters or managing workloads, as it enables customers to either expedite or delay replication resources based on their specific needs and criticality of business operations. The default behavior assigns the highest priority to ongoing replications to minimize their performance impact when new replications are initiated. The MEDIUM priority allows new replications to gradually catch up with existing ones, while the LOW priority is suitable for less time-sensitive scenarios, such as setting up hot and cold clusters. The new priority setting can be adjusted without disrupting existing replications and is accessible via the CLI or REST API, providing users with enhanced control over their resource management and potential cost savings in cloud deployments.