[MetroMPG]

Firefox (for desktop) has a "Save page as" option, where you can choose to save with images or without. When you open the local file without an internet connection, the images load from the local copies, if you chose that option.

Also: you can change your personal forum settings (user control panel) to show up to 40 posts per page, and reduce the number of pages in long threads that you have to save.