It's not clear exactly how this was generated, but emacs ships with a full-featured XML editor as the default XML mode (https://www.emacswiki.org/emacs/NxmlMode

It's not clear exactly how this was generated, but emacs ships with a full-featured XML editor as the default XML mode (https://www.emacswiki.org/emacs/NxmlMode https://www.emacswiki.org/emacs/NxmlMode) that includes syntax and schema validation, which probably impact the XML benchmarks.