  Results on the computational efficiency of 2-flavor staggered Wilson fermions
compared to usual Wilson fermions in a quenched lattice QCD simulation on
$16^3\times32$ lattice at $\beta=6$ are reported. We compare the cost of
inverting the Dirac matrix on a source by the conjugate gradient (CG) method
for both of these fermion formulations, at the same pion masses, and without
preconditioning. We find that the number of CG iterations required for
convergence, averaged over the ensemble, is less by a factor of almost 2 for
staggered Wilson fermions, with only a mild dependence on the pion mass. We
also compute the condition number of the fermion matrix and find that it is
less by a factor of 4 for staggered Wilson fermions. The cost per CG iteration,
dominated by the cost of matrix-vector multiplication for the Dirac matrix, is
known from previous work to be less by a factor 2-3 for staggered Wilson
compared to usual Wilson fermions. Thus we conclude that staggered Wilson
fermions are 4-6 times cheaper for inverting the Dirac matrix on a source in
the quenched backgrounds of our study.
