I have just finished running some quick performance evaluations on 15.7 using my project (the code isn't public yet, but it'll hopefully be by the end of next week).
I don't have a consistent testing methodology for previous runs. This time I can monitor visually the measured performance.
Trusting my gut feelings, I'd say the performance has degraded slightly. In terms of peak performance the difference can be up to 10% but I'm recalling from memory.
BUT what I can tell for sure is this driver produces less variability. It is very steady; I like it. In terms of averages the difference is likely less marked.
Besides, with my card approaching 70C I suspect some throttling might be going on. I will test more next week.