From Wirecutter's review:
"As of an August 2017 update to the Backblaze software that increased the number of threads it uses even with default settings, the backup performance is significantly better compared with the previous version. With default settings, my tests showed throughput of 19.58 Mbps—not the fastest of the services I tested, but quite respectable. At that rate, you could back up about 220 GB of data per day. However, you don’t have to stick with the defaults. If you click Settings and then go to the Performance tab, you can uncheck Automatic Threading/Throttle, move the Manual Throttle slider as far as you like toward Faster Backups, and even choose the number of backup threads (from 1 to 20) from a pop-up menu. Backblaze warns against choosing a number higher than 6, but I was able to go all the way up to 20 on my test machine without any apparent ill effects. With performance bumped up as high as it would go, my tests showed throughput of 22.4 Mbps—again, not quite the fastest of the group, but plenty fast for most people. "
And for iDrive:
"Of any app I tested, IDrive had the best throughput, 27.1 Mbps, at its default settings (which don’t throttle upload speeds). And you can share, via email or social media, files you’ve backed up; recipients get a link to download the file."
Wow, now I am considering iDrive instead. They also offer a special rate to previous Crashplan users, 5TB for $7 for the first year. Not bad!!