How many is tons? I've not had such problems with hundreds of snapshots. There are reports on the btrfs list with problems involving many thousands. I have no idea how ZFS snapshots perform when there are hundreds to thousands.

The other thing that matters a ton is kernel version, the development is so heavy there are thousands of insertions+deletions per kernel cycle that even in a year it's ordinary to consider those kernels "old" on the list. Most distros by default use old kernels by Btrfs development standards. The exception is Fedora, and openSUSE who do lots of backports explicitly to support Btrfs.