The claim is that it's 2% to 5% in most general uses on systems that have PCID support. If that's the case then I'm willing to bet that databases on fast flash

The claim is that it's 2% to 5% in most general uses on systems that have PCID support. If that's the case then I'm willing to bet that databases on fast flash storage are lot more impacted then this and pure CPU bound tasks (such as encoding video) are less impacted. The reality is that OLTP databases execution time is not dominated by CPU computation but instead of IO time. Most transactions in OLTP systems fetch a handful of tuples. Most time is dedicated to fetching the tuples (and maybe indices) from disk and then sending them over network. New disk devices lowered the latency significantly while syscall time has barely gotten better. So in OLTP databases I expect the impact to be closer to 10% to 15%. So up to 3x over the base case.