LLNL
`std::endl` is expensive
Using std::endl to terminate a line is expensive. See e.g. https://en.cppreference.com/w/cpp/io/manip/endl. std::endl flushes the stream, and this can be quite expensive, especially when the output is redirected to a file on a shared file system.
Is there a particular place where we're using std::endl to terminate a line that you have in mind? Or are you opening this ticket so that we look at all instances across Conduit?
I looked at the code, and it seems that conduit is using std::endl instead of \n everywhere. I don't think that's a good programming guideline. It might be worthwhile changing all std::endl to \n, and adding explicit calls to std::flush where necessary (if necessary at all).
Yes, the flush included in std::endl has a price. We can revisit -- we also have fmt that can help
