If instead the 64 reactions with estimated barriers less than 50 kcal/mol are first checked (i.e. TS optimisation followed by IRC) with GFN2-xTB the number of DFT searches can be lowered significantly. We tested three different criteria for further DFT refinement: 1) The TS connects 3-hydroperoxypropanal to the correct product, 2) The TS connects to 3-hydroperoxypropanal, and 3) the TS connects to either 3-hydroperoxypropanal or the correct product. Here the correct product is that used to create the TS guess using the RMSD-PP method. Using criterion 1, 2, and 3 reduces the number of DFT refinements to 5, 19, and 30, respectively. Using criterion 1, Reaction 2 is not identified as the corresponding TS is shown to connect 3-hydroperoxypropanal to formaldehyde and oxiranol (N1a, Figure ) whereas using criterion 2 or 3 reactions 1-3 and the new reaction (Figure ) are all identified by the DFT refinement. If GFN1-xTB is used instead, criterion 1, 2, and 3 reduces the number of DFT refinements to 6, 17, and 33, respectively and the all subsequent DFT refinements identify Reactions 1-3, but not the new reaction.