Perf improvement: json_middleware

[pr-benchmarks]

Scenario	Environment	Date	Old RPS	New RPS	Change	Deviation	StDev	Dependencies
json_middleware	Json 10k 2- Trends Cobalt Cloud Linux	06/01/2025 09:45:25	174,009	174,573	0.32 % (564) 👍	3.08 σ	182.76	Changes Name Version Diff Microsoft.AspNetCore.Antiforgery.dll 10.0.0-preview.6.25279.106 -> 10.0.0-preview.6.25281.101 dotnet/dotnet@92e8051...8041120 Microsoft.AspNetCore.App 10.0.0-preview.6.25279.106 -> 10.0.0-preview.6.25281.101 92e8051...8041120 Microsoft.NETCore.App 10.0.0-preview.6.25279.106 -> 10.0.0-preview.6.25281.101 dotnet/runtime@92e8051...8041120

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