[Perf] Linux/x64: 3 Regressions on 6/22/2026 9:59:16 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [4e663ebdcf1759b3bc787d069977a2bf35b90779](https://github.com/dotnet/runtime/commit/4e663ebdcf1759b3bc787d069977a2bf35b90779)
Compare | [929ca574fb3f6ac7c9683f5d5983bbf2bf56b3ae](https://github.com/dotnet/runtime/commit/929ca574fb3f6ac7c9683f5d5983bbf2bf56b3ae)
Diff | [Diff](https://github.com/dotnet/runtime/compare/4e663ebdcf1759b3bc787d069977a2bf35b90779...929ca574fb3f6ac7c9683f5d5983bbf2bf56b3ae)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Text.Json.Tests.Perf_Deep

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [WriteDeepUtf16 - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 808.34 ms | 934.74 ms | 1.16 | 0.15 | False | | |
|

• [WriteDeepUtf16 - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 829.64 ms | 933.71 ms | 1.13 | 0.20 | False | | |

![graph]()
![graph]()
[Test Report]()

### Repro
General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

```cmd
git clone https://github.com/dotnet/performance.git
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Text.Json.Tests.Perf_Deep*'
```

### System.Text.Json.Tests.Perf_Deep.WriteDeepUtf16(Formatted: False, SkipValidation: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.Json.Tests.Perf_Deep.WriteDeepUtf16(Formatted: False, SkipValidation: False)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

[Profiling workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/profiling-workflow-dotnet-runtime.md)
[Benchmarking workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/benchmarking-workflow-dotnet-runtime.md)

---

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [4e663ebdcf1759b3bc787d069977a2bf35b90779](https://github.com/dotnet/runtime/commit/4e663ebdcf1759b3bc787d069977a2bf35b90779)
Compare | [929ca574fb3f6ac7c9683f5d5983bbf2bf56b3ae](https://github.com/dotnet/runtime/commit/929ca574fb3f6ac7c9683f5d5983bbf2bf56b3ae)
Diff | [Diff](https://github.com/dotnet/runtime/compare/4e663ebdcf1759b3bc787d069977a2bf35b90779...929ca574fb3f6ac7c9683f5d5983bbf2bf56b3ae)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Text.Json.Tests.Perf_Basic

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [WriteBasicUtf16 - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 137.95 μs | 160.33 μs | 1.16 | 0.23 | False | | |

![graph]()
[Test Report]()

### Repro
General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

```cmd
git clone https://github.com/dotnet/performance.git
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Text.Json.Tests.Perf_Basic*'
```

### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: False, SkipValidation: False, DataSize: 10)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

[Profiling workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/profiling-workflow-dotnet-runtime.md)
[Benchmarking workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/benchmarking-workflow-dotnet-runtime.md)

Start with the benchmark sources src/benchmarks/micro/libraries/System.Text.Json/Utf8JsonWriter/Perf.Deep.cs and Perf.Basic.cs, then run the provided benchmarks_ci.py filters under the documented benchmarking workflow. Compare the baseline and test results to identify the regression; done means the cause is understood and the affected benchmarks no longer regress.

Written by the indexing model from the issue text.