This was the situation I was having a few years ago and switched to another's defrag program. Today I installed Defraggler---instead of the one I'm using on my laptop--- on a HP 2000 Notebook for a neighbor [that I 'Reset Your PC' on and have only added 3 programs from Piriform] and it is having the same issue that I had experienced in the past.
Defragmenting (32%) has been sitting there for over 6 hours now. The Remaining Time has been getting lower though. What has me concerned is the amount of time that it is taking to defrag, compared to other programs that I have tried.
Used space: 43.3 GB
Free space: 229.8 GB