Observing the dynamics of the list, I have to ask: who is JB and why is he/she so worried about VM performance under BtrFS?
Fedora is not a Linux you recommend for someone who doesn't know what they are doing and, if you know VM performance sucks with BtrFS, please, by all means, add another partition and use ext4 (or 3 or 2 or XFS or anything you think may offer you better performance)
Fedora is not a Linux you recommend for someone who doesn't know what they are doing and, if you know VM performance sucks with BtrFS, please, by all means, add another partition and use ext4 (or 3 or 2 or XFS or anything you think may offer you better performance)