Obj export extremely slow

Hi there!

I am experiencing a slowdown very hard here while exporting simple obj mesh from Rhino 6.
It takes a long time to export files into obj, while Rhino 5 was fast.

I mean, for a 10Mb final obj file it took 10 minutes to save. This is not normal.
It takes time even if I have already previewed the mesh.

I don’t know,I am using the same setup as Rhino 5, but here it takes ages.
Am I missing something? Could it be a bug?

Thank you everybody and have a nice day


Hi filippo - by previewing the mesh, do you mean you meshed the object first in Rhino (Mesh command) then exported the mesh directly? Or is the meshing for the obj taking place as part of the export process. It would be good to know if the delay is in the export or in the meshing part.


Hi Pascal!
I’ve just tried to export objs in three different ways and it is always slow.
The procedure I used were:
1- straight export from nurbs, without previewing the mesh:
2- stragiht export from nurbs, previewing the mesh from the polygon mesh options;
3- meshing the nurbs in rhino, then exporting that meshes to obj.

For a file with less than 50 closed polysrf (not very intricated, final mesh has 50522 faces), and a final obj file of 7Mb it took almost two minutes to save.

Hope to be helpfull somehow!

Let me know if it could be usefull to share the files I am using.

Thank you for time.

Any news? The situation is going crazy here. It takes ages to save an obj.

Thank you guys

Hi Filippo- can you please send the Rhino file to tech@mcneel.com, to my attention? I’ll see if I can reproduce the problem.



Hi, I am also having the exact same problem. I’m working on a much bigger file and export times for an obj is huge. Would it have anything to do with the new ngon feature?

Thanks in advance for any help!

Hi MIke - can you tell if there is any difference if you do not check the box for ‘Create nGons’? I do not see any delays so far here.


I just tested it and it also took about 10 minutes for the export even with the ‘create ngons’ box unchecked. Another weird thing- the file that eventually did export with the ‘create ngons’ box checked would not import into 3ds max, the obj import process froze on the ‘building scene’ stage. The version that was exported with ‘create ngons’ box unchecked imported into max fine.

Sorry Pascal I haven’t had the time yet to prepare the file, but I still have the same issue. I will send you the file as soon as I have it ready! Thank you for your support

Hi Mike - if you can send us a file that is slow, that would be helpful - send to tech@mcneel.com, to my attention. The smaller the better, for troubleshooting, as long as it shows the problem. If the file is large, zip and upload to




Has this been resolved?

I’m having the same problem, we’re having to export our files back to rhino 5 to export objs as the slowdown for multiple part exports is crazy! We’ve had this problem with multiple files as well. (largest file was 93mb total and only exporting a small section of this). I’ve noticed that rhino 6 also seems to have other slow downs on commands like undo and copy to clipboard and I was wondering if this is part of a larger issue


currently evaluating Rhino 6, and noticed the same slow .OBJ-Export Problem.
After some fooling around i noticed something. I almost exclusively work with a networked shared drive, and export is only slow and writing only a few kB per second (30-40 kBps) when i export the File to the drive.

If I export to my local drive instead, Rhino writes the file almost instantly.

I have noticed something similar in other programs (i think autodesk Meshmixer suffers from this aswell). It’s weird because normal Read/Write on the network drive is 50-100mBps, maybe it’s how the files themselves are written which is not suited for network transfer.

I guess writing the file in larger blocks or save to the userfolder in blocks first and then transfer to save location might fix this, but i can just guess.

Just so you know that might be another factor that causes slowdown, it might not necessarily be something in the Rhino files themselves.

Hope this helps someone. Cheers!

Hello - thanks for the details… we are still trying to track this down - for at least some users the lag is there on local drives as well.



Has this been solved or does anyone have a suggestion for a workaround?

It took me 20 minutes to save a 20MB model and then when I tried to save a very similar model, it took me 2h to save only 1MB of that file. Then I aborted it…

Hi - are you saving to a local disk, to a network, or to a disk location that is synchronized on the net?
Does this happen with any file and any file format?

Hi Wim,

I have tried to save it both on a server and on a backed up disk location. Will try a non-synchronised disk as well.
I have tried both .3ds and .fbx.

EDIT: I was able to save it as a .dxf file but it did not include the faces, only the lines of the model. I don’t know if that has to do with the file format?

Hi there!

I must say that I am not experiencing the slowdown anymore. Many months have passed since the last time I encounterd this problem, I even forgot about it.
Just to be clear, I did nothing by myself. I simply did the updates regularly and one day it was gone. I don’t know. Maybe I am a bit redundant, but is your Rhino updated?
Have a nice day everyone

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