Revit Family keeping them workable

[jelmer.eekman]

Gentlemen,

We have a couple of very large families with loads and loads of shared nested families wich all use association to the host family and we are now at a point that these families get less and less workable. I searched the internets for a list of things that slow down or speed up families but no succes. 

I know for sure that arrays in families exterminates working speed, even if arrayed objects are lines. But are there other known things that slow them down?

Do parameters wich are controlled by formula's slow families down? And is the degree of difficulty or the number of other parameters used in this formula of any influence? I noticed that when I threw away all of the formula's in one of our families it size dropped down ca 2 MB.

Is it better to use visibility parameter or exchange types with a family type parameters. 

Do roundings in geometry make families heavier? 

General question is; is there a list of things that make families less workable. 

Thanks!

[L.Maas · Accepted solution]

In general the more complicated a family the bigger the impact on performance. When you have lots of objects (e.g elements, nested families) and you change a parameter somewhere Revit has to 'recalculate' the family to see what the impact of the parameter will be on all the other elements/families. The more detailed a family is the more Revit has to work to put it on the screen. So lots of small lines and curves usually have an impact.

As you already mentioned arrays are often slow. Also (large, many) voids can have a negative impact on performance.

In your case I would advise to look at the possibility to simplify your family and research if it can be split in several smaller families. You probably have experience with your current family. So look if some parts are rarely used and can be separated in to a new 'special' family. Also look if the elements used can be simplified (e.g. more boxy, less voids). 

What I have done in some projects is that I used a simplified family in the beginning and at the end of the process replaced it with a detailed version (e.g for rendering). However this process needs careful planning as otherwise the replacement can be problematic.

[Zsolt.Varga · Accepted solution]

Hi Jelmer, 

I actually don´t know of a document focusing particularly on Revit families and performance, and I also haven´t found such a document, however there are so many docs and posts out there I couldn´t swear there´s no such thing in the world. 

We definitely have though the white paper about Revit 2017 performance here: 

Model Performance Technical Note

Generally

EnlInt is right - basically everything which forces Revit to calculate more data has an inpact on its performance. 

That being said, there is a couple of things we can think of such as: 

• Rounding means more geometry to calculate so the family is more cpu intensive to display
• Nested families
• Linking of parameters between host and nested families
• Constraints
• Imported dwg files
• Over modelling
• Voids

These all have a bad influence on the performance, however it is rather hard to tell what level of performance-drop is considered still being "healthy".

The best way is probably testing the performance and considering changes to the families as EnlInt correctly suggested in his post. 

I hope you found this information helpful. 

Please, don´t forget to mark comments as "Accepted solution" in case you found them helpful - this way you can help other users searching for an answer for the same question. 

Best regards,

[Zsolt.Varga]

Hi Jelmer, 

As an extension of my previous comment: 

Please, also consider to check the following as possible causes of slow performance: 

• Model Distances
• Model Corruption
• Disable the Addin/Extensions 
• Family Corruption > (Please, reload the impacted families while having Audit on)

Best regards,

[Zsolt.Varga]

Hi Jelmer, 

We haven´t heard back from you in this forum thread for a longer time. 

In order to point other users with the same questions to the valuable information EnlInt and myself have collected in our posts, I will go ahead and mark those answers as accepted solutions now. 

Thanks again for participating in the Autodesk Forum. 

Best regards, 

[jelmer.eekman]

I'll do a study on this one day and will report back.