perf: make methods synchronous in ObjectLifecycleService

[TimothyMakkison]

• Remove async keyword making methods synchronous
• Use ValueListBuilder in RegisterArgumentsAsync, using the newer Task.WhenAll(ReadOnlySpan<Task>) overload where possible.
  • Older versions of .NET either return a single Task or create an array.

Before

After

[thomhurst]

Summary

This PR optimizes ObjectLifecycleService by removing unnecessary async keywords and using ValueListBuilder for better performance in RegisterArgumentsAsync.

Critical Issues

None found ✅

Suggestions

Consider Task.WhenAll behavior on older .NET versions

In RegisterArgumentsAsync, the fallback for pre-NET9 targets allocates a new array via .ToArray(), which reduces the performance benefit of using ValueListBuilder. However, this is only for older .NET targets where the span-based Task.WhenAll overload does not exist, so it is a reasonable trade-off. The NET9+ path gets the full benefit.

Performance validation

The PR description shows allocation improvements in a screenshot. Since this touches a hot path (object registration), the performance improvement is welcome and aligns with TUnits Performance First principle.

Previous Review Status

No previous comments found.

Verdict

✅ APPROVE - No critical issues. The changes are clean, correct, and improve performance:

• Methods that were unnecessarily async are now synchronous (eliminating state machine overhead)
• ValueListBuilder reduces allocations on the happy path
• ValueTask.AsTask() is correctly used for the cleanup method
• Unused using directive correctly removed
• All changes preserve existing behavior while improving efficiency