two windows or two instances of civil 3d 2012

[lambertb]

Anyone have pros and cons of using two instances versus two windows? I ahve alignments and corridors in seperate files so I am always using both. Does two instances utilize multi-core processors better?

Thanks.

[tcorey]

I try to avoid two instances of AutoCAD as each one loads into memory. If you use a single instance and open two drawings, you only have the AutoCAD program loaded into memory once.

[Neilw_05]

I don't typically open 2 sessions at once but I can see the advantage of that if you have more then one display and want to work with the data side by side.

If there is nothing in the knowlegebase it would be worthwhile to file a support request on that one and post the response.

[dgorsman]

If you have enough RAM, and you can let one application chew on a long-term processing job while working on the other, you might get away with it.  Just remember, though, that Civil3D has a single registry location for each profile, so while you have two sessions running if they are using the same AutoCAD profile there may be some "last one out wins" problems with settings storage.  Otherwise it may be more efficient to structure the work process.

[lambertb]

Here is some guidance from C3D support.

I understand you would like to know if there are any performance benefits or inhibitors based on having two instances open or multiple drawings in one instance of Civil 3D. Although we have no official tests or documentation of this, I can discuss my personal observations.

Typically in support I will have at least 3 versions of Civil 3D up and running, and each with multiple drawings open.

This is how I operate throughout the day. Typically this will run smoothly, but if I do experiencing some lag it is typically due to the drawing size or the amount of references attached and not really due to the amount of windows open. That’s not to say that sometime I need to close down all applications and reboot my machine to clear memory once in a while as you can definitely see performance improve after that.

So although this is subjective, if you have a rather robust machine, it should be able to handle multiple drawings and multiple applications open at the same time. Test machine has 12 GB RAM and Xeon 2.67GHz processor. Please let me know if any of this helps.

[Neilw_05]

Thanks for posting the support response.

Good info.

[BrianHailey]

As others have suggested, I would go with 1 instance of Civil 3D with multiple drawing open unless you need to have access to data within the two drawing simultaneously. You can't open a dialog box (such as editing a style) in one drawing and then, with it still open, switch to another drawing. If you need that ability, two instances would be the way to go.