I fixed the problem by correcting a mistaken setting under the Bootup tab of MSCONFIG, in Win10. I have a dual-core processor, and had set the Number of Processors to “2”. In fact, I have one processor and two cores. The correct setting is the have this set to “1”, then uncheck the CPU tick box, and reboot.
I stumble on that when I found that I was running on 1 core and 1 logical CPU, instead of 2 cores and 2 logical CPUs. When I fixed this (as above), it fixed my problem of the CPU being throttled to 800 MHz (instead of 2400 MHz) everytime I came out of hibernation under battery power.