The reason for keeping asserts on is to have checks for memory access to metadata, as the checking function is inside the ASSERT. This can be separated so the asserts can be disabled and the memory checks still in place. Now implemented in the patchset https://lore.kernel.org/linux-btrfs/cover.1643904960.git.dsterba@suse.com/ The first patch is an optimization that should bring back the performance, so that's something to backport regardless of the rest of the series.