I run a basic benchmark on my machines:
time echo "scale=3000;4*a(1)" | bc -l
This computes Pi to 3000 decimal places. The general expected time in my experience is 35-60 seconds on a Raspberry Pi B+, 2, 3.
One of my machines is giving 24 seconds, which is far out of the ordinary. This machine is a Raspberry Pi 3. My other Pi 3s give a consistent 48 seconds. I have checked the governor (it is ondemand), boot config parameters and rebooted to make sure its clean.
I am not asking for alternative benchmark systems. I do know what I have is shakey (does not test multiple CPUs etc...), but the differences are surprising and consistent.
What could be causing such anomolous behavior?
UPDATE: I have started looking at the problem again. I used a fresh install of the OS and added extra programs one by one. It seems the slowdown happens when using the packages
python-mpi4py. I am investigating further.