Today I opened a 18000x18000 image made by the Hubble Space Telescope(yes, the size is correct), using a dual-Opteron x86-64 workstation, Nvidia Quadro with 128 MB ram, and 4 GB of system ram, using Debian/Linux kernel 2.6. GQview worked flawlessly, allowing to browse the image in 1:1 zooming factor with amazing performance, while other programs (Gimp, xli...) just coundn't handle it.
For adventurous readers, the image is here (24 MB JPEG or 385 MB TIFF):
Thanks for this great program! :)