gthumb very slow with 1000+ tiff fax files

gthumb is working with jpg files, but there is a problem with tiff fax files.

I have a folder with more than 1000 files with FAX 4 encoding (so only black and
white), the files are small (about 50kb), but since they are scans of A4 sheets
at 600 DPI, the pictures are about 5000 x 6900 pixels.

gthumb cannot normally be used to 'walk' through these files in picture view
mode (using 'space' and 'backspace'), because the RAM memory usage goes up to
97% and de processor is most of the time 100% busy, doing a lot of HardDisk I/O.

Starting gthumb to show the thumbnails: memory goes from 75MB to 83MB, that's okay.
Either scrolling through the thumbnails or viewing the first picture: RAM memory
goes from 83MB to 449MB, that's a lot. Viewing 20 more pictures will increase
the swap usage beyond 1GB.

OS: Ubuntu 5.10
gthumb: 2.6.5 (thumbs: 64x64, zoom: low quality)
CPU: K7, with 512MB
kernel: K7

http://bugs.gnome.org/show_bug.cgi?id=323873: http://bugs.gnome.org/show_bug.cgi?id=323873