Issue solved with MMA Version 11.3.0 for Raspberry Pi running Raspbian Stretch June 2018 (2018-06-27):

Pi 3B+ V11.3 score is 0.13 and it took 107–110 seconds (test 9 & 15 both around 8 seconds each)

Pi 3B+ V11.2 score is 0.03 and it took 454 seconds (test 9 172 s & test 15 105 s)

Tests 4, 5, 8 are 3-times faster now and test 14 is slightly over 4 times faster. Other tests are about the same as before.

Wow. Great improvement on the same hardware. Especially, but not only, the very slow computations are now greatly accellerated. Great news indeed.

Thanks. Thats at least two votes now. Its clear that the RPI is really making progress with the hardware. I would hope that Mathematica would advance with it. The RPI 3 is great and let's put it to good use.

There's a Raspberry Pi 3? I never saw anything on the tech review sites.

A good idea to check the temperature/cpu clock. Alas, the problem evidently can't be fixed with a couple of heat sinks and a fan.

I installed a power monitor on the USB power cord, the Raspberry Pi's temperature monitor and the CPU clock monitor on the taskbars of both computers.

I updated both the Raspberry Pi 2 and a Raspberry Pi 3 to Jessie (uname -r -> 4.1.13-v7+) and wolfram-engine ($Version -> 10.3.1 for Linux ARM (32-bit) (January 11, 2016).

The benchmark summary is as follows:

Model                Benchmark        Total Time        Voltage        Current    Temperature Range    CPU clock
Raspberry Pi 2       0.011                1248                >5. V          0.3-0.4 A      <49 deg C                 900MHz
Raspberry Pi 3        0.022                 842                >5. V           0.3-0.4 A      <50 deg C                    -

These data are less confusing to me in that the 3 is faster than the 2 running the same versions of the software (to the extent arranged by $sudo apt-get install). Evidently, there's no quick fix.

Finding whether the 3 is going to be usable for my projects will have to wait. Doing linear algebra on the GPU wold be a worthwhile step though.

Cheers, Fred Klingener

Here are a couple of plots showing the performance as a function of frequency for Mathematica and also python3 (first 20000 digits).The procedure used the overclock menu in raspi-config. For G/L 7 Wheezy the options were 700, 800, 900, 950 and 1000. For G/L 8 Jessie the pi2 had two options 900 and 1000, and the pi3 had only 1 setting 1000. The Mathematica benchmarks significantly deteriorate for 10.3.1/Jessie. The Python benchmarks are all better for Jessie, excluding Linux as the problem.