Various sources (https://btrfs.wiki.kernel.org/index.php/Status, https://wiki.debian.org/Btrfs) warn that "too many" snapshots, possibly as few as 12, can degrade performance. OTOH, Marc Merlin's talk identified snapshots as one of btrfs's killer features. And the status page https://btrfs.wiki.kernel.org/index.php/Status doesn't note any performance issues with subvolumes/snaphshots.
As a practical matter, do I need to limit the number of snapshots? Does it matter what kernel version I'm running? I have a VM running 4.0.9 and am looking to install Debian Buster which is 4.19 at the moment (4.18 on my first install). Thanks. I'd appreciate if you'd cc me on replies. Ross Boylan