Blocks make model extremely slow

Hi there,
I am working in a file that contains about 400 block instances containing 119 block defintions, which partly are nested. Usually I never experienced trouble working this way, but this file in particular is very very slow.

When I explode all block down to their bottom, I get 20000 objects. It seems a lot, but it
s acutally no problem to work with.

I found a similar isssue here (outside this forum).

Working in wireframe mode is quite okay when working in with the blocks, but I just wonder where this comes from?
Aren’t he blocks there to make the models lighter?
And what strategies would make sense to avoid a laggy model?



Hi Tobias - I guess the best would be for us to have this model and any external files linked to the model - we can take a look and see if we can see the same problems- please upload to

with a link back to this topic in your comments.


@pascal, I jut uploaded the file.
Thanks in advance.

Hi Tobias - I see the slowness here as well, thanks.


@pascal , do you have any idea yet?

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Hi Tobias - I do not know, myself - the example has been added to the bug tracker for the developers.


This is one of the most annoying problems nowadays in the program. Blocks are really common in drawings and still haven’t found a solution. I usually edit them individually in another file of Rhino, an empty file.

Edit.: if i set the Antialiasing option in the OpenGL tab to “None” the problem solves

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I have the same issue on the mac. When I start working with blocks the software slows down significantly.

Would love to see a block manager where I can work with AutoCAD dynamic blocks, order them to the alphabet and insert them via drag & drop. Blocks are a simple feature but a very powerful one .)

@OXII, I think the issue appears then the nesting level of the block is very deep. At least might be one of the reasons I observed and could maybe identify as a source of this problem…

blocks are generally a problem, since eh version 7 i think, i am not sure why nobody reported this here but there are many complaints about it. it has become unusable on a bit older computers (and probably just heats up the faster ones unnecessarily) to the point where you have to explode blocks or hide them away to be able to navigate at least. there are several topics regarding this issue on discourse.


I’ve noticed since I first started using Rhino many years ago, that it will slow down quite a bit after may revisions of a model. My work around years ago was to copy everything and paste into a new file.

I stopped doing this over the years, as I believe the power of computers go so that it became unnecessary…


Today I found myself frustrated with the slowness of my model, and after purging and deleting tiny lines/etc - I tried my old trick, and it worked! Brand new session with everything cut and pasted into it (layouts imported) the model is a lot quicker. Is there some other kind of purge command that can do this without the cut and paste trick?

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@chris19 nice approach, I will test this.
@pascal, has there been any development or insights?

I can repeatedly confirm that deeply nested blocks are quite a problem.

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That could very well be it! I was working from an imported file that had a ridiculous amount of nested blocks.

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I have the same experience with Rhino 6.
If you explode them, the performance improves slightly.
Got a help suggestion from Pascal/Wim to upload the .3dm file in question, but sadly my company never allowed it.

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Ideally, it would be nice to be able to explode all the nested blocks, while keeping the top level parents intact.

@pascal are there any updates to this issue yet?
I am having the same problem at the moment, so I just wanted to see what’s the status.

Hi Tobias -

We have that issue on the list as RH-65013. This is not visible to the public because of the model that is attached to it. It’s currently on the “Future” list.

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