The two approaches are stenciling (what you call monomorphisation) and dictionaries. Stenciling/monomorphization increases binary size, compilation time and TLB

The two approaches are stenciling (what you call monomorphisation) and dictionaries. Stenciling/monomorphization increases binary size, compilation time and TLB/cache pressure. The dictionaries-only approach has more runtime cost. This hybrid is a middle ground of both.