define 'a little cost in performance' that you (and everyone else)would be willing to loose.
doing a fsync on ext3 (what the ext maintainers believe is nessasary to get to the disk to be safe) can take several seconds. if you want a rename to provide that sort of guarantee you need to be willing to pay that sort of cost for every rename.
ext3 never provided the guarantees that people think it did. it just happened to work if you didn't crash too soon after doing a rename.