Don't create a copy of the in memory stream.

src/Foundatio/Storage/InMemoryFileStorage.cs

@@ -71,7 +71,7 @@ public async Task<Stream> GetFileStreamAsync(string path, StreamMode streamMode,
 
                 // Copied from SaveFileAsync
                 _logger.LogTrace("Saving {Path}", normalizedPath);
-                byte[] contents = ReadBytes(stream);
+                byte[] contents = stream.ToArray();
                 if (contents.Length > MaxFileSize)
                     throw new ArgumentException($"File size {contents.Length.ToFileSizeDisplay()} exceeds the maximum size of {MaxFileSize.ToFileSizeDisplay()}.");