Regressions in System.Text.Tests.Perf_StringBuilder

### Run Information

Architecture | arm64
-- | --
OS | Windows 10.0.19041
Baseline | [11bf8a782d27dd0f614dd0da03b27ab025933320](https://github.com/dotnet/runtime/commit/11bf8a782d27dd0f614dd0da03b27ab025933320)
Compare | [8471eecd98e5493e3fbc8bcc34662310ef8762eb](https://github.com/dotnet/runtime/commit/8471eecd98e5493e3fbc8bcc34662310ef8762eb)
Diff | [Diff](https://github.com/dotnet/runtime/compare/11bf8a782d27dd0f614dd0da03b27ab025933320...8471eecd98e5493e3fbc8bcc34662310ef8762eb)


### Regressions in System.Text.Tests.Perf_StringBuilder

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio | Baseline ETL | Compare ETL
-- | -- | -- | -- | -- | -- | -- | -- | -- | -- | --
[Append_Span - Duration of single invocation](<https://pvscmdupload.blob.core.windows.net/reports/allTestHistory/refs/heads/main_arm64_Windows 10.0.19041/System.Text.Tests.Perf_StringBuilder.Append_Span.html>) | 27.39 ns | 43.81 ns | 1.60 | 0.10 | True | | |

![graph](<https://pvscmdupload.blob.core.windows.net/autofilereport/autofilereports/02_02_2022/refs/heads/main_arm64_Windows%2010.0.19041_Regression/System.Text.Tests.Perf_StringBuilder_1.png>)
[Test Report](<https://pvscmdupload.blob.core.windows.net/autofilereport/autofilereports/02_02_2022/refs/heads/main_arm64_Windows%2010.0.19041_Regression/System.Text.Tests.Perf_StringBuilder.html>)

### Repro

```cmd
git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net6.0 --filter 'System.Text.Tests.Perf_StringBuilder*'
```
<details>

### Payloads

[Baseline](<https://helixdi8s23ayyeko0k025g8.blob.core.windows.net/helix-job-c76574df-7bd9-4817-b9c8-86a73ed11756045c70d8d334ab48c/4d3a8b34-561d-4b5b-bbce-e3d8293296f3.zip?sv=2019-07-07&se=2022-02-27T12%3A37%3A08Z&sr=c&sp=rl&sig=pn3PurI6RlC0pBlKooRtA8vhfqEhH0ZhhzIOf67h2ww%3D>)
[Compare](<https://helixdi8s23ayyeko0k025g8.blob.core.windows.net/helix-job-249fcd34-5ab3-4cfd-9cfa-6afbf4688e35d2f8c0be14248148c/6e12c483-8833-4bae-9cd8-a983d332aad2.zip?sv=2019-07-07&se=2022-02-28T04%3A28%3A36Z&sr=c&sp=rl&sig=rX0eWxEgTQ21MrIQ%2FkO6GlJEz8x6Cx0AhGdnJbpqytE%3D>)
### Histogram

#### System.Text.Tests.Perf_StringBuilder.Append_Span

```log

```
### Description of detection logic
```IsRegressionBase: Marked as regression because the compare was 5% greater than the baseline, and the value was not too small.
IsRegressionChecked: Marked as regression because the three check build points were 0.05 greater than the baseline.
IsImprovementBase: Marked as not an improvement because the compare was not 5% less than the baseline, or the value was too small.
IsRegressionBase: Marked as regression because the compare was 5% greater than the baseline, and the value was not too small.
IsRegressionChecked: Marked as regression because the three check build points were 0.05 greater than the baseline.
IsRegressionWindowed: Marked as regression because 43.806113539524524 > 28.626101433626996.
IsChangePoint: Marked as a change because one of 1/28/2022 4:34:00 PM, 2/2/2022 11:04:24 PM falls between 1/25/2022 5:49:56 AM and 2/2/2022 11:04:24 PM.
IsRegressionStdDev: Marked as regression because -38.4072881703715 (T) = (0 -46.3456689212713) / Math.Sqrt((0.7290073887378425 / (26)) + (4.322788422199066 / (19))) is less than -2.016692199226234 = MathNet.Numerics.Distributions.StudentT.InvCDF(0, 1, (26) + (19) - 2, .025) and -0.7209753526364372 = (26.929885341049392 - 46.3456689212713) / 26.929885341049392 is less than -0.05.
IsImprovementBase: Marked as not an improvement because the compare was not 5% less than the baseline, or the value was too small.
IsChangeEdgeDetector: Marked as regression because Edge Detector said so.

```

### 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)

</details>


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Regressions in System.Text.Tests.Perf_StringBuilder #64751

Run Information