Perf improvement: fortunes_dapper, json_middleware

[pr-benchmarks]

Scenario	Environment	Date	Old RPS	New RPS	Change	Deviation	StDev	Dependencies
fortunes_dapper [Fixed]	Fortunes Platform Dapper 1- Trends Database Intel Linux	03/27/2025 09:03:14	399,913	414,944	3.76 % (15,030) 👍	2.82 σ	5,323.80	Changes Name Version Diff PlatformBenchmarks.dll 1.0.0 -> 1.0.0 aspnet/Benchmarks@83ff5f5...249eaff Microsoft.AspNetCore.App 10.0.0-preview.4.25171.5 -> 10.0.0-preview.4.25175.4 15cc4f4...ab38f49 Microsoft.NETCore.App 10.0.0-preview.4.25173.3 -> 10.0.0-preview.4.25174.9 dotnet/runtime@a50b4a0...659321f
json_middleware [Fixed]	Json 400k 2- Trends Gold Windows	03/27/2025 10:06:41	11,748	11,775	0.23 % (27) 👍	2.36 σ	11.51	Changes Name Version Diff Json.dll 1.0.0 -> 1.0.0 aspnet/Benchmarks@83ff5f5...249eaff Microsoft.AspNetCore.App 10.0.0-preview.4.25171.5 -> 10.0.0-preview.4.25176.5 15cc4f4...c752467 Microsoft.NETCore.App 10.0.0-preview.4.25173.3 -> 10.0.0-preview.4.25174.9 dotnet/runtime@a50b4a0...659321f

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