As far as I can tell, the only difference between a .bak file and a .cpr file is the extension–so they are the exact size that the project-file was at the time of the autosave.
I was messing with an older 2015 project a few weeks ago. I can’t remember the Cubase version, 9 or 10, maybe, anyway, whatever was current in 2015.
The original CPR is 4,668 KB.
The Cubase 14 CPR is 4,676 KB.
I just saved an empty Cubase 9.5 project: 80 KB.
An empty Cubase 14 project is 93 KB.
I would imagine the extra features since 9.5 would require some kind of place-holding structure(s) in the project file.
I do find though, that the more Kontakt instances/libraries I have in a project, the bigger the CPR. EG, the last track I uploaded here, the CPR is 28,148 KB.
I don’t use Autosave!
(All “Pro” versions of Cubase.)
Well, the culprit seems to be my template file which is about 340K. I did an update for C14 and it is now saved to 300K. The tracks I have in there are all disabled, I don’t know why is it such a large file?
I hear you. With big projects, data size can spiral out of control with Autosaves.