PS: Question on huge size images

[Daelin]

My star chart map is 7500x5000 and that has around 300 layers. It does run rather slow, when zooming and such, but its not unbearable. And my machine is about 3 years old (Vista/AMD 4400/4GB.
I've recently upgraded to PS CS5 and it definitely runs smoother than previous versions.

[Fransie]

If you want a resolution of 300dpi, you'd end up with a file of about 14000 x 9000 pixels. That's darn big. I strongly suggest to go the vector way, and give Illustrator or Xtreme a try. Obviously, you'll need to learn some new techniques to get good results.