Loop through multiple images to convert to base64 to Http POST - Garbage Collection

Hi,

My app needs to loop though potentially a large number of images for upload, during which I convert to Base64 using the following code:

        try
        {
            using (var stream = file.GetStream())
            {
                var bytes = new byte[stream.Length];
                await stream.ReadAsync(bytes, 0, (int)stream.Length);

                var base64Image = Convert.ToBase64String(bytes);

                int base64EncodedSize = 4 * bytes.Length / 3;
                var sizeInKb = base64EncodedSize / 1000;

                Debug.Write($"OPOCDebug {DateTime.Now.ToString("hh:mm:ss.fff")}: ConvertImageAsync MediaFile String Length {sizeInKb}Kb");

                return base64Image;
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }

The above is called via a foreach loop on the Image collection and I'm seeing lots of the following in the Debud window which is slowing down the overall process:

09-24 09:52:03.544 I/.telerik.OPOCv(28042): Explicit concurrent copying GC freed 5(79KB) AllocSpace objects, 0(0B) LOS objects, 64% free, 3MB/9MB, paused 192us total 29.213ms

I've read the follwiong post:

https://markolazic.com/prevent-xamarin-forms-signaturepad-memory-leak-android/

...which states: "Every garbage collection (explicit or not) has performance implications, because it blocks all the threads until finished." Can any one suggest how I refactor the above to prevent the need for GC or any alternative on how to perform the requirements?

Thanks in advance.