Upload large image files to Azure

Question

I am currently writing a program that takes image files from my data base and uploads them to Azure storage here is what I have written:

 public async Task UploadAssetsAsync(Func<GridFSFileInfo, string> prefixSelector, List<GridFSFileInfo> files, Func<GridFSFileInfo, Task<Stream>> streamOpener, Func<string, Task> progressAction)
 {
 if (flyersContainerClient == null)
 throw new Exception("Container client not initialized. Please initialize before doing blob operations.");
 var q = new Queue<Task<Response<BlobContentInfo>>>();
 progressAction?.Invoke($"{files.Count}");
 foreach (var f in files)
 {
 var pathPrefix = prefixSelector(f);
 var blobClient = flyersContainerClient.GetBlobClient($"{pathPrefix}/{f.Filename.Replace("_copy", "")}");
 IDictionary<string, string> metadata = new Dictionary<string, string>();
 var blobhttpheader = new BlobHttpHeaders();
 if (f.Filename.EndsWith("svg"))
 {
 blobhttpheader.ContentType = "image/svg+xml";
 }
 var stream = await streamOpener(f);
 if (pathPrefix == "thumbnails")
 {
 var format = ImageFormat.Jpeg;
 Bitmap cropped = null;
 using (Image image = Image.FromStream(stream))
 {
 format = image.RawFormat;
 Rectangle rect = new Rectangle(0, 0, image.Width, image.Width);
 cropped = new Bitmap(image.Width, image.Width);
 using (Graphics g = Graphics.FromImage(cropped))
 {
 g.DrawImage(image, new Rectangle(0, 0, cropped.Width, cropped.Height), rect, GraphicsUnit.Pixel);
 }
 }
 stream.Dispose();
 stream = new MemoryStream();
 cropped.Save(stream, format);
 stream.Position = 0;
 }
 q.Enqueue(blobClient.UploadAsync(stream, new BlobUploadOptions { HttpHeaders = blobhttpheader, TransferOptions = new Azure.Storage.StorageTransferOptions { MaximumConcurrency = 8, InitialTransferSize = 50 * 1024 * 1024 } }));
 }
 await Task.WhenAll(q);
 }

This is the fastest way I think it could run but it still seems sluggish as it can be uploading up to 2000-3000 images. What am I missing?

• Peter Csala: <irony>I always love to review those code fragments where we have variable names like q, g, f, etc. </irony>
• Peter Csala: Have you performed some kind of profiling? What did it say which part of your method is the bottleneck from performance perspective?
• BCdotWEB: metadata is defined but never used. Naming doesn't follow Microsoft's rules (e.g. blobhttpheader). A Bitmap needs to be disposed.