On 10/15/2017 11:39 AM, William F Pokorny wrote:
> On 10/14/2017 01:25 PM, E-mailyvo s gmx.net wrote:
> 
> Note. These days timing is very sensitive to how the cache(s) on the 
> system are being used when you do timing renders. 5-6x slower seems 
> extreme for cache impacts. I've seen as much as about 2x slower on a 
> busy system on occasion, but never more - and you are seeing similar 
> across multiple renders...
> 

Off doing other things when I remembered years ago I did have a 
situation where my other than trivial renders were running many times 
slower than expected. My CPU fan had clogged & died unknown to me and my 
Intel i7 throttled the CPU frequency back substantially to where it was 
running right at the TDP temperature. Modern CPUs do this slow down 
thing so as not to cook themselves. Older CPUs sometimes do not and I 
know folks here have fried such CPUs with POV-Ray renders in the past.

The turbo feature of many CPUs complicates timing too - my i3 doesn't 
have it.

Anyway, suppose just an off the wall thought maybe these huge slow downs 
are due temperature and self throttling CPUs. Though that would mean 
3.8.0 code runs hotter than the 3.7.0 code and enough so that the CPU 
throttles down. A long shot reason I suppose, but the 5-6 slower seems 
so out there given some of what you ran was faster. The -32% faster is 
quite large for a 3.7 to 3.8 improvement from what I've seen that was 
faster.

Bill P.

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