.NET Core 2.1 DirectoryInfo.EnumerateFiles() Performance is Slower than .NET Framework

[ONeill45]

Issue Title

.NET Core 2.1 DirectoryInfo.EnumerateFiles() Performance is Slower than .NET Framework

General

I have a .NET Core 2.1 Web API that is being built as a replacement for an older .NET Framework MVC Web Application (.NET Framework 4.5).

One of the responsibilities of this application is to take in a directory and search template and return the top 10 results, ordered by most recent. This is being accomplished using System.IO.DirectoryInfo and the EnumerateFiles() method:

List<FileInfo> fileInfos = new DirectoryInfo(directory).EnumerateFiles(fileTemplate)
.OrderByDescending(f => f.LastWriteTime).Take(10).ToList();

However, I am noticing that this search is much, much slower in .NET Core than in .NET Framework. I created two console apps with the same code, one .NET Framework and one .NET core, to compare run times. Below are the results in .NET Framework:

And then the results in .NET Core:

Can anyone help me understand why there is such a dramatic decrease in performance?

[MarcoRossignoli]

better move to https://github.com/dotnet/corefx

/cc @JeremyKuhne, @pjanotti

[Petermarcu]

Issue moved to dotnet/corefx #32098 via ZenHub