[FWTools] MrSID Reader performance?

[Jason Birch]

FrankW wrote:

> I suspect you are seeing cache thrashing in which case
> you will want to set the GDAL_CACHEMAX environment 
> variable to a fair sized number (eg. 200).

Thanks Frank, that has helped immensely.

Is there a downside to setting that value really high, other than taking
the memory away from other system processes?  

I don't see any real performance difference between 200MB and 500MB
(about 100KB/s output), so this seems like it's one of those things that
doesn't matter unless you hit a certain threshold, but hitting that
threshold is something I'd like to avoid in the future :)

I think when I set it to 1000 it behaved as if it was not set at all.

Jason