Lightroom bulk download performance degradation

With the previously-available Adobe Lightroom Downloader app, I could download (incrementally) my entire library in a couple of hours. 

The new mechanism, requiring an email with literally hundreds of .ZIP file links, took about 8.5 days to complete the full download the last time I tried it. This is approximately 0.01% the speed of the older mechanism, and it makes the functionality near useless for a daily or even weekly backup, especially since it requires manual intervention for each and every file.