  Running large-scale computer codes for huge fluid flow problems requires not
only large supercomputers but also efficient and well-optimized computer codes
that save the resources of those supercomputers. This paper evaluates the
high-performance implementation of the recently proposed Lattice Boltzmann
Method (LBM) algorithm with a fixed viscosity and relaxation time $\tau=1$
called Tau1. We show that the performance of the Tau1 algorithm is almost
$4\times$ higher than other state-of-the-art standard LBM implementations. We
support this finding by detailed complexity analysis and performance study
based on the code with several optimizations, including multithreading, vector
processing, significantly decreased number of divisions, and dedicated memory
layout. We studied its performance in porous media flow in the
three-dimensional model of porosity-varying porous medium to make it sound in
the physical context. We find performance drops with porosity, which we link to
the fact that memory access patterns change dramatically with the increased
complexity of the pore space. In contrast to standard LBM implementations,
where the performance drops with the number of lattice links, the processing
speed of the new algorithm measured in fluid node updates per second is almost
constant regardless of lattice arrangements.
