I think the improvement really has something to do with the re-install of CBD with Chrome which I did after the AMD driver upgrade
I am nearly absolutely sure (that is >99%), that those re-installs can't have changed anything by themselves.
CloneBD does not, like many other applications, depend on hundreds of external DLLs with varying versions, etc...
So a certain version of CloneBD will always behave the same, no matter how often you reinstall it.
And Chrome - I can't think of a way in which Chrome would influence CloneBD at all, they have nothing in common.
It's most likely a coincidence.
I am not sure what you mean about "compression"? If the source size is well under 50, usually CBD does not seem to compress. If close to,or even over, 50GB, the scale shows that it is being lowered and then compression comes into play?
A blu-Ray of, say 40 GB, would not be compressed? In any case here is a log of recent burn.
During the encoding process, CloneBD tells you in the bottom area of the screen whether it's compressing or not.
It's also shown right before on the output page:
Here I preselected "BD-R DL", but the input disc is too large, so CloneBD has to compress.
In the following case I manually set the "Resulting size" slider to maximum, so CloneBD indicates "no compression".
But it will also not fit on to a BD-R DL disc, which only has roughly 48GB of space.
That's the major difference for you. "No compression" means, that your AMD card is not required for compression, so it will work.
The other case DOES try to compress using hardware acceleration.
It is possible, that your specific AMD card can't handle the AVC codec, someone from Elby should maybe confirm or deny that.
Then you'll have to disable hardware acceleration (and live with very slow transcoding) or grant yourself a newer, more powerful graphics card. In that case I would suggest abandoning AMD in favour of an nVidia GTX 10xx card - AMD is rubbish for video encoding.