No, that's common too. Think childNodes traversal. So you do need something in addition to the linked list to make sure that at least in-order childNodes trav

No, that's common too. Think childNodes traversal. So you do need something in addition to the linked list to make sure that at least in-order childNodes traversals are O(N), not O(N^2), in common cases. Memory use is a concern, but not the overriding one. A very large web page (e.g. the HTML spec) has maybe 500k nodes. An extra 4 words of memory per node, on 64-bit, then translates to ~16MB of RAM. If you look at actual memory consumption on that page, you will see that 16MB is not _that_ huge a deal, unfortunately. The big problem with a doubly linked list is loss of memory locality and the resulting cache misses on traversal. That's something browsers are still working on figuring out, honestly; there is various work around trying to arena-allocate nodes and whatnot, but it has various drawbacks as well (e.g. arenas being kept alive by a single node, which you can fix by making your nodes relocatable in memory, but then you need to use handles instead of pointers, etc, etc).