Comment by jsheard

I think Intels E-cores are quite a bit smaller than the Zen 4c/5c cores, maybe at that scale it's prohibitive to even double up the register file? That's required even if the logic is double-pumped. AIUI the small Zen cores are mostly the same design as the big ones, just with less cache, silicon layout retuned for density rather than speed, and the removal of the 3D Cache stacking vias, while Intels small cores are clean-sheet designs with next to nothing in common with their big cores so they have to opportunity to shrink them a lot more.