LAPACK(zsptrf), using Complex has no speed improvement comparing with Complex

For function LAPACK(zsptrf) to solve matrix LU, if the matrix data type is Complex<float>, the speed should be faster than Complex<double>. But I did not see the improvement. I use the version mkl-10.3.9. Will the new version has this benefit? Newest version is mkl-11.2.2.

Thanks.