When it comes to finding synonyms for "most reducing," several options exist. One option is "largest reduction," which emphasizes the size or magnitude of the reduction in question. "Significant decrease" is another phrase that could be used; this emphasizes the importance of the reduction. Terms like "major cut" and "substantial drop" also highlight the significance of a reduction. Alternatively, "maximized decrease" or "optimal reduction" may suggest that the reduction has been maximized to its fullest potential. Ultimately, the choice of synonym depends on the context in which it's being used, but each of these options has the potential to effectively convey the idea of significant reduction.