My Amazon EC2 (Windows / t2.Large) server uploads ~200K files to S3 (bucket is in the same region as the server). After a few hours of ~100 files a minute the upload slows down to ~30 files a minute with no obvious reason. Pausing the process for a few hours will make it go fast again. Does Amazon put a limit on this traffic? Any other reason for the speed loss?

Here is my upload code:

        string S3_KEY = S3TargetFileName;

        S3_KEY = S3FolderName + "/" + S3_KEY;

        S3_KEY = S3_KEY.ToLower();
        PutObjectRequest request = new PutObjectRequest()
        {
            CannedACL = S3CannedACL.PublicRead,
            BucketName = BucketName,
            Key = S3_KEY,
            FilePath = LocalFullPath
        };
        var client = GetS3Client();
        client.PutObject(request);