1. It is a lot faster for a lot of stuff, as long as your kernel has proper
swapping behavior. This happens because tmpfs can avoid a great deal of
costly operations that other filesystems with backing store need to perform
(such as the need to keep metadata in sync on the backing store).
2. It will waste more virtual memory space than your regular filesystem with
a backing store, as it needs to keep all data in virtual memory (even if it
happens to be swapped). This *can* be a problem on 32-bit systems.
Interesting. Is there any downside? Why isn't this default?