Bob wrote:
> It *looks* fixed, for me anyhow in the few ways I tried it.
> 
> Render speed is another matter. Without AA the two seem similar enough until 

The problem is basically the crackle cache. The bug before was due to the
cache not working properly. The slowdown now is due to the performance of
the cache now that it is working (a different caching method is used).

The problem is basically that the cache is memory-intensive, and allocating
memory during render is something we really like to avoid, as it requires
locking; the more threads, the more contention for the lock.

I've just spent some time playing with this and have improved the
performance somewhat by using memory pools, but it's still not as fast as
just not using the cache at all. (By that, I mean in wall clock time; using
no cache at all renders faster in terms of waiting for a render if you have
several cores, but burns more CPU time because of the lack of a cache).

It's a difficult problem to solve cleanly. I'll have another stab at it in
a few days.

-- Chris

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