6000x2000 is quite a bit, but more importantly which 'bells and whistles' are running on the settings side of things?
If it absolutely has to be that large, try going down in quality, keeping the important settings at reasonable levels.
Copy pasting this from other topic:
Here are some tips I gave on another topic to set up a reasonably fast render, which will still give decent results:
http://archicad-talk.graphisoft.com/viewtopic.php?p=267934#267934
If you 'just' need to print out a nice render on A4 sheet or letter, I can recommend setting up a 300 dpi render at 195x135 mm (excuse me if I don't do inches), this is a nice classic photo aspect ratio that scales up fine to around 200 dpi for A4 print, which is good enough on a decent printer in my experience. If you want more of a panoramic ratio, just decrease the 135 mm to something like 95 mm.
If you are doing a very large render for something like a billboard, people will be watching that from a large distance, so you can get away with around 100 dpi for whatever the size of the billboard is.
If you are doing a render for 'on screen' presentation, you can even get away with 1280x720 renders. I use this on the rare occassion I am asked to do video clips and you need to render out a lot of frames.
Erwin Edel, Project Lead, Leloup Architecten
www.leloup.nlArchiCAD 9-26NED FULL
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