Upload large image files to Azure

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?