I got this reply from HTC Support saying that the HTC Vive Wireless Adapter IS incompatible with AMD CPUs and that they are trying to find a workaround:
Dear Chris,Thank you for contacting US and Canada Vive Support. We always appreciate hearing from our customers!We completely understand the frustration on this issue, Chris. Nevertheless, we would like to explain to you what's going on. In this case, we're afraid the Vive Wireless Adapter is not compatible with AMD processors, therefore, the latency and stutters. We really do apologize for this compatibility issue, Chris. However, you can be sure we're doing our best to check on a work-around with this. ...
I have replied asking for more details. It's hard to imagine that with the same instruction set and with similar features that AMD CPUs would behave so differently than Intel CPUs. I'd very much like to know what the issue is, under the hood.