Chambers <bdc### [at] yahoocom> wrote:
> I fully 
> expected multithreading to involve some overhead, making it slightly 
> slower on a single-processor machine

  A bit off-topic to this particular thread, but multithreading on a
single-processor computer does not necessarily mean slower execution
(even if by a really small margin). In fact, it may even mean slightly
faster execution.

  Multi-threaded applications which perform calculations and lots of
disk I/O might actually considerably benefit from multithreading even
in a single-processor computer. This is because while one thread is
waiting for disk I/O to complete, another thread can continue using
the CPU. With one single thread the process would be stuck during I/O.

  In a heavily CPU-oriented application such as POV-Ray you probably
won't get basically any speedup. The only case where there might be
a measurable difference is when rendering big animation frames which
render at a very high speed and which are saved in an uncompressed
file format (such as bmp).
  I'm not saying this is so (without actual measurements it's
impossible to say), but in theory it could be possible.

  So the problem you are experiencing is quite clearly related to
something else. Perhaps the new code has some big overhead in
recursive tracing calls? I can't say.
  However, since it's (most probably) nothing related to multithreading,
it can probably be fixed.

-- 
                                                          - Warp

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