I try this, but 1 pass takes hours. How long will it take? It's on my OS drive. I usually abort, and whenever I do, Windows makes a Huge Shadow copy of it.
Wipe speed depends mostly on processor speed and size of free space.
If you have a lot of free space on OS drive why not shrink it so it wipes faster? Repartitioning is effortless with Windows Disk Management.
I shrank this OS(C:) drive to 96GB, therefore the ≈58GB free space wipes in 12 mins, 1 pass. The balance of allocated space is divided into backup and storage volumes which rarely need defragging or wiping.
By aborting you prevent CC from deleting the wipe cache. Delete the folder(s) or file(s). 
You may wish to disable the VSS service while you do a wipe.
Wiping the free space is not recommended unless you are selling/giving away your drive. (or have some deep-dark secret to hide )
. . . or have some deep-dark secret to hide
We do. Corporate homework is always sensitive.
You may wish to disable the VSS service while you do a wipe.
VSS runs during wipe?
I usually abort, and whenever I do, Windows makes a Huge Shadow copy of it.
"I usually abort, and whenever I do, Windows makes a Huge Shadow copy of it."
I don't know what the wipe cache consists of, but don't think it's tied to the VSS. The only way to find out is to disable VSS, run a wipe for a few minutes and abort.
VSS triggers whenever many files are changed or created on a drive (FWIU) so that's probably why it gets triggered by the wipe
I can find abundant info on the VSS process, but none that wiping free space would invoke the request to write a shadow copy. So I succumbed to curiosity and wiped the free space using DriveWiper on the OS [C:] volume, which is the only volume I have VSS enabled. ☐Stop VSS in Defraggler\Settings\Options\Advanced is not ticked.
Win7 64bit. Before wipe Windows showed 57.3GB free, Defraggler showed 57.4GB free. Command Prompt showed 13.28GB VSS shadow storage.
After completing an 11 minute wipe Windows and Defraggler show 58.8GB free space, Command Prompt shows 12.135GB VSS shadow storage. Per CCleaner no new Restore Points were created.
Amazing. Not only was there no increase in VSS, it actually decreased by 1.145GB.
Strange. Before I disabled it, even a defrag would cause VSS to start its work. Perhaps larger drives are more prone to it?
I got an AMD E-450 APU with Radeon™ HD Graphics
4GB's of RAM
And 300Gb HD
It takes me roughly 30mins to 1 hour to finish. I can give 1 step to speed this up.
Run MSConfig, easily found by typing MSConfig in the search or New Task in Task Manager.
Click the startup tab, and uncheck ALL the boxes, click apply, restart. Run scan, and then turn back on all system startup items. This helps reduce my time from 18 hours to 30mins to 1hour. I hope this helps.
For step by step guide, follow this link: MSConfig Steps