MongoDB 2.6 has been released with new majors features as primary target, but it also improve performance.
- efficient use of network resources
- oplog processing is 75% faster
- classes of scan, sort, $in and $all performance are significantly improved
- bulk operators for writes improve updates by as much as 5x.
- Text Search Integration
- Insert and Update Improvements
- A new write protocol integrates write operations with write concerns(The protocol also provides improved support for bulk operations)
- A new authorization model that provides the ability to create custom User-Defined Roles and the ability to specify user privileges at a collection-level granularity.