We maintain several shared data-structures on ServiceContext. In particular, the following are modified as part of constructing and destroying instances of OperationContext:

• The unordered map that maps operation ids to clients, and a mutex that synchronizes accesses to this data structure.
• The registry that allows checking out unique operation ids.

Sharing these across many cores result in frequent cache-line evictions and performance regressions (see PERF-4626 for detailed analysis and a PoC that measures potential gains from partitioning these structures).