I'm not really sure what the solution to these sorts of problems are. I was working on a fairly new desktop computer using CS5. I wasn't running any programs besides Photoshop (because I tend to be a ten thousand tab queen), and my desktop has eight gigs of highspeed DDR3 RAM. Fortunately, a banner is a once every two years kind of expense, so I won't have to make another this size any time soon. I got the banner printed using Vistaprints, and I am fairly happy with the quality, although that is a much much later post.