Wipe Free Space - Temporarily disabled

I recall last year sometime I used the Wipe Free Space feature on an old laptop with an HDD drive. While this feature did increase my overall storage capacity, I found it resulted in the HDD running considerably slower even after I tried various options like Optimize, Defrag and more. I even reinstalled Windows from my factory partition.

I don't know if what I experienced is in any way related to the current issue, although I see in the notes mentioning the reason for temporarily disabling is that this feature is deleting more than it should.

WFS would only increase the storage capacity if it wiped live files - wouldn't it?