So far we used the term configurations in its full generality, since the FCIQMC algorithm is not restricted to a specific basis and can use Slater-Determinants (SD) as well as spin eigenfunctions. In the following we will restrict ourselves to SDs because we make use of the Slater-Condon rules in this work. In the SD basis there exist several algorithms for the sampling of double excitations with different trade-offs between efficiency and memory demand, notable ones include: (a) the Cauchy-Schwarz excitation generator by the Alavi group, (b) the heat-bath Power-Pitzer method by Neufeld and Thom, and (c) the precomputed heat-bath (PCHB) method 1 by Holmes et al.. PCHB is the foundation of the work presented in this document.