Use o3tl::sorted_vector instead of std::set, the sets are fairly small here, and cache effects dominate. Takes the test for this test file from 7.6s to 0.6s Change-Id: I7fad3cd20ab1df01b11273e5f841109fc846433e Reviewed-on: https://gerrit.libreoffice.org/c/core/+/202152 Tested-by: Jenkins Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>