How tight are those loops really and how complex are your instructions? I'd suspect you're blowing out the cache and leaning on a single decoder due to the nat

How tight are those loops really and how complex are your instructions? I'd suspect you're blowing out the cache and leaning on a single decoder due to the nature of the instructions. Particularly if these are SIMD instructions even if you sped up or paralleled the decoders you'd be up against later pipeline latencies very quickly anyways, at that point, are you actually measuring a real bound?