I am a Mac user and their app is java based and used a terrible amount of RAM and CPU time for me.
I can't say i've noticed this on any of my installs. I will monitor this more closely in future.
I do like the fact that crashplan keeps deleted files forever (or until you tell them to go away) where as Backblaze only keeps a deleted file for 30 days before it disappears
I actually like this, it means that i can't accidentally delete a file beyond all recovery, although i do understand why one would be less than enthusiastic about that feature.
But the end result was that my Mac was running like a dog w/ Crashplan but not with Backblaze
Well as my mentor once said:
A backup that's not tested regularly isn't a backup, and a backup that degrades user performance is a waste of effort.
so, i can agree with you there at least.