An analysis of .NET library performance from version 6.0 to 11 RC reveals mixed results regarding execution speed. Comparing .NET 10.0 to 7.0 across 46 operations, 9 showed performance gains, 13 slowed down, while others remained within the margin of error or showed no verdict.
The study highlights that while repetitive operations in .NET 10.0 accelerated by 14–35%, initial calls and object creation experienced slowdowns of 39–64%. For long-running services, these trade-offs are generally beneficial, though short-lived processes may face increased cold-start times.
The research investigated the impact of AI coding agents, specifically the Copilot coding agent, which opened 1,734 pull requests in the dotnet/runtime repository between May 2025 and October 2026. Data shows that performance regressions in 11 RC were primarily caused by human-authored code, including a single line change in the configuration binder.
A specific regression in the configuration binder, which increased binding time for POCO classes, was traced to a new attribute check. Maintainers acknowledged the issue but noted that reflective binder performance is not a primary priority, recommending the use of source generators for performance-sensitive scenarios.
Another performance shift in the 11 RC release involved a 15% increase in the first DI resolve, which was linked to a fix for a deadlock issue. The change, which introduced a ThreadStatic HashSet to track dependencies, was identified as a necessary trade-off for improved stability.
