... giving me tension ...
I told you you need to be patient 
The 95% display is expected (although not ery helpful).
Now for the one with 128 GB how long it will take I am thinking may be hours ?
With the experience of the first snapshot, I'd guess ~1min/GB!?
As a best practice keep snapshots only as long as required, e.g. for a critical update or a backup and delete them as soon as possible. Snapshot may not only have influence on performance, but can also cause disk space issues.
André