aspnetcore: Proxy scenario perf regression

Actually in CoreFx, but opening in aspnet until I get more information

Updated

3.0.0-preview-27408-1 -> 3.0.0-preview-27409-1

Microsoft.NetCore.App / Core FX https://github.com/dotnet/corefx/compare/c2bbb6a5ee5ff67e5e8353e154d7b4c4f2f83143...e1c0e1d4928b27113cdb2d021f4abbb202c9892a

Microsoft.NetCore.App / Core CLR https://github.com/dotnet/coreclr/compare/a51af0838709ca81b51bee236865a39b31f68f41...4e5df11e42457b6201545e672a2f3d1eb18e47e7

Command lines:

dotnet run -- --server http://10.10.10.2:5001 --client http://10.10.10.4:5002 `
-j ..\Benchmarks\benchmarks.httpclient.json -n HttpClientFactory --sdk Latest --self-contained --aspnetcoreversion 3.0.0-preview3-19116-01 --runtimeversion 3.0.0-preview-27408-1

dotnet run -- --server http://10.10.10.2:5001 --client http://10.10.10.4:5002 `
-j ..\Benchmarks\benchmarks.httpclient.json -n HttpClientFactory --sdk Latest --self-contained --aspnetcoreversion 3.0.0-preview3-19116-01 --runtimeversion 3.0.0-preview-27409-1