@Deozaan - Bvckup runs all its copying activity at lowered CPU priority, meaning that it yields to other programs that need CPU. The slowdown you saw most likely meant that Minecraft was saturating CPU on its own, so there was virtually no CPU time left for anything else. I am not familiar with SpiderOak, but Bvckup does need some CPU time to generate supporting data for servicing delta copying later on. I am also guessing that generating new world translates into creating large amount of data, which in turn means lots of things to copy during the initial backup. The incremental (delta) updates afterwards should be fairly painless as per your previous experience.