Performance: MockedItemBenchmark.ReadItemExists;[Type=Stream] takes longer to run as expect in Preview mode.

[philipthomas-MSFT]

Description

Release pipeline is showing a larger number than expected for preview on MockedItemBenchmark.ReadItemExists;[Type=Stream]. Should be 26018.25, but 27381 (5.24%)

To Reproduce
Run command-line locally. Observe and compare results from preview and non-preview. If the numbers are off, then we must determine why there is a gap.

Command-line

Release (non preview)

dotnet.exe run --project Microsoft.Azure.Cosmos.Performance.Tests.csproj --configuration Release --no-restore --framework net6.0 --allCategories=GateBenchmarkReadItemExists -- -j Short -m --BaselineValidation

Results

Current benchmark results: {
  "MockedItemBenchmark.ReadItemExists;[Type=OfT]": "34527.75 (2.67%)",
  "MockedItemBenchmark.ReadItemExists;[Type=OfTCustom]": "34536.25 (2.68%)",
  "MockedItemBenchmark.ReadItemExists;[Type=OfTWithClientTelemetryEnabled]": "34527.75 (2.68%)",
  "MockedItemBenchmark.ReadItemExists;[Type=OfTWithDiagnosticsToString]": "56717.25 (3.04%)",
  "MockedItemBenchmark.ReadItemExists;[Type=Stream]": "26766 (2.87%)"
}

Release (preview)

dotnet.exe run --project Microsoft.Azure.Cosmos.Performance.Tests.csproj --configuration Release --no-restore --framework net6.0 --allCategories=GateBenchmarkReadItemExists -- -j Short -m --BaselineValidation /p:IsPreview=true

Results

Current benchmark results: {
  "MockedItemBenchmark.ReadItemExists;[Type=OfT]": "34529.25 (2.67%)",
  "MockedItemBenchmark.ReadItemExists;[Type=OfTCustom]": "34534 (2.67%)",
  "MockedItemBenchmark.ReadItemExists;[Type=OfTWithClientTelemetryEnabled]": "34543.25 (2.72%)",
  "MockedItemBenchmark.ReadItemExists;[Type=OfTWithDiagnosticsToString]": "56784.75 (3.16%)",
  "MockedItemBenchmark.ReadItemExists;[Type=Stream]": "26765.5 (2.87%)"
}

Expected behavior
Both preview and non-preview tests for ReadItemExists, stream, should have the same performance metrics.