FastR also uses native BLAS and LAPACK libraries. It should be possible to link it with Intel MKL as well.

We didn't want to include comparison to R-3.5.X, because FastR itself is based on the base library of 3.4.0, but the results for GNU-R 3.5.1 almost the same as for R-3.4.0.

AFAIK ALTREP is not used that much yet inside GNU-R itself. They can now do efficient integer sequences (i.e. 1:1000 does not allocate 1000 integers unless necessary), which would save a little bit of memory in this example, but that's about it. FastR also plans to implement the ALTREP interface for packages. Internally, we've been already using things like compact sequences.