Raspberry Pi 3 & 3+ speed issues

Hi,

I recently noticed this discrepancy in the reported versus actual speed of 
Raspberry Pi 3s.

otter:
[     1.000000] simplebus0 at armfdt0: Raspberry Pi 3 Model B Plus Rev 1.3
[     4.267737] mue0 at uhub2 port 1
machdep.cpu.frequency.current = 1400
time ./primes
1000000, 15485863
12.256u 0.000s 0:12.70 96.4%	0+0k 0+0io 0pf+0w

jasper:
[     1.000000] simplebus0 at armfdt0: Raspberry Pi 3 Model B Rev 1.2
[     3.220862] usmsc0 at uhub1 port 1
machdep.cpu.frequency.current = 1200
time ./primes
1000000, 15485863
12.151u 0.000s 0:12.16 99.9%	0+0k 0+0io 0pf+0w


So they're basically both running at the same speed. At 600 MHz, they both 
take about 24.5 seconds to count the first million prime numbers, meaning 
that the Pi 3+, which says it's running at 1400 MHz, is really running at 
1200 MHz.

I don't know if this has always been the case, but I have vague memories 
of the 3+ being slightly faster in real world. Any ideas, anyone?

NetBSD 11.0_RC6, aarch64, recent start*.elf, fixup*.dat and so on.

Thanks,
John