Analyzing XKCD: Click and Drag
blackhole12.blogspot.com
blackhole12.blogspot.com
This statement is a bit flawed since he doesn't differentiate between almost empty frames and frames with much detail. It obviously took longer to create frames with a lot of details than empty frames or frames with little detail.
Still, it's an interesting post. Randall clearly put a lot of time and effort into creating the "Click and drag" world.
I haven't been able to find libraries that can handle the full 165888x65536 10 gigapixel image.