Time results much longer than running out of nix for tampi+isend+oss+task+simd branch

Saiph experiments report different times if running from or outside nix. nix exp hash: 3dg4zca8kpmxh9vkl85q9vhk2xh7f6qm-experiment

Runs at mn4 under the following environment:

## clang compilation:
module purge
module load gcc/9.2.0
module load intel/2020.1
module load impi
module load java/8u131
module load mkl
module load ompss-2/git
export BOOST_HOME=/apps/BOOST/1.68.0_cxx14/INTEL/IMPI
export SAIPH_HOME=/home/bsc28/bsc28017/repos/saiph/saiphv2/cpp/src
export VTK_HOME=/apps/VTK/8.0.1/GCC/IMPI
export VTK_VERSION=8.0
export LD_LIBRARY_PATH=/apps/PM/ompss-2/git/lib/:$LD_LIBRARY_PATH


## using TAMPI:
module load tampi

and using mpirun!