>This is something the tiff files do not do, memory usage increases until
>it is all gone..fairly quickly on some tiffs. The tiff
>format  "structure was designed to be easily extendible", and can vary,
>though the files I get are from a service that scans drawings and
>supplies tiffs to members, should be typical.

Greg,
this smells like a memory leak bug. 
If you can reproduce this on a regular basis, could you file a bug report in bugszilla?
Please add steps to reproduce the problem and in case the problem only shows up with some particular images, please attach an example of pictures that can be used to debug it.

Thanks
  Michele