From the documentation of the Eigen library [0]: > If the quaternion is used to rotate several points (>1) then it is much more efficient to first convert it t

From the documentation of the Eigen library [0]: > If the quaternion is used to rotate several points (>1) then it is much more efficient to first convert it to a 3x3 Matrix. Comparison of the operation cost for n transformations: > - Quaternion2: 30n > - Via a Matrix3: 24 + 15n So really it depends on what you're doing (admittedly here it is 3x3 not 4x4) [0] https://eigen.tuxfamily.org/dox/classEigen_1_1QuaternionBase.html#aae0b06729e20b45be97dc829f506914d https://eigen.tuxfamily.org/dox/classEigen_1_1QuaternionBase...