I had heard about this, though when it comes to sensitive data I'd rather be doing too much as opposed to finding out that one overwrite isn't enough when somebody is dining out in Prague at my expense.
I'm quite pleased that the PC is still usable when running CCleaner, but if it was sacrificing overwrite speed by limiting how much power it used, I'd find that quite counter-productive.
I had a feeling that might be the case. I suppose I'll have to use a less complex algorythm for the big wipes.
It's about 800GB once you subtract the OS and backup partition. Haven't put a great deal of data on it yet, so I suppose I must either have a fast disk or the software isn't doing it properly.