New issue 665: The "all" particle type duplicates memory https://bitbucket.org/yt_analysis/yt/issue/665/the-all-particle-type-duplica... Matthew Turk: Currently, the "all" particle type duplicates a large amount of memory. We should push this into the IO layer as a conceptual field, and avoid any usages of the `_field_concat` that we can avoid. Responsible: MatthewTurk