Before revision:  When the input is the WMG, to our knowledge, the fastest algorithm for computing all possible winners in the Schulze method uses a folklore reduction to the All-Pairs Bottleneck Paths (APBP) problem and runs in O(m^{2.69}) time, where m is the number of candidates.
After revision:  When the input is the WMG, to our knowledge, the fastest algorithm for computing all possible winners in the Schulze method uses a folklore reduction to the All-Pairs Bottleneck Paths problem and runs in O(m^{2.69}) time, where m is the number of candidates.