Hmm, no, I can't. This was something I had observed in practice over the years (i.e. several orders of magnitude performance difference between AES-128 and AES

Hmm, no, I can't. This was something I had observed in practice over the years (i.e. several orders of magnitude performance difference between AES-128 and AES-256 from my PHP implementations), and "your CPU only supports AES-NI for 128-bit keys" was the explanation I was given at the time. I haven't observed this recently, and I'm on newer hardware, so the explanation made sense. In attempting to identify which CPUs were affected by this limitation, I've discovered that I was grossly misinformed about this. I'm going to update the article to redact this, ASAP. UPDATE: Redaction applied.