Carbonite kills my Mac

Version 2 (prime) significantly hangs/slows down my iMac. I've been corresponding with their tech support for months, to no avail. They tell me my backup's too large, but this wasn't stated in their marketing materials when I upgraded. This problem wouldn't occur if Carbonite could be prevented from starting upon booting the computer, but their engineers somehow can't do this.

It takes several minutes for the app to load and then connect before I can halt it & quit. An alternative is to uninstall and then reinstall when needed, which "ain't great."

Their support agents can't escalate trouble reports to their "escalation unit." They have to be called, and I've not been impressed with their expertise on these calls. (They're all very nice and concerned BTW, but something's wrong at the top, IMO).

If I hadn't spent so much money on the upgrade and data transfer charges, I'd stop using Carbonite in a nanosecond. In the meantime, I'm storing a hd-backup with a trusty relative located out of our fire hazard area.