Revit is very slow, but CPU is only at 30%

[kh_jea]

We've got a bit of a problem here at the office.

We're working on files which size ranges from 700MB to 1.4GB (I'm talking very large offices, stadiums,...)

In one project Revit (Revit 2017.2) is responding very slow, e.g. when moving a wall several cm's it takes about 2-3 min for Revit to complete the action.

There are no other applications running and no other plan views opened in Revit.

The CPU is at about 30% (RAM is 32GB).

Why in't Revit using more CPU? Can we force it to use more?

If 30% is all Revit needs, why is it still being so slow?

[Anonymous]

Depends on your modeling habits.  Are there lots of in-place modeling?  That will slow things down considerably.  Also make sure you have memory intensive items placed in its own worket, such as seating or anything else with large arrays.

Some may say it is the filesize...but I have worked on many projects that are over 1G (yeah, stadiums) and they worked just fine with 32G of Ram...  But you may want to look into separating some parts of the model into another.  Such as stadium vs areas with rooms.

[kh_jea]

The file we were working on yesterdag, practically has no in-place-models. It consist mainly out of floors, columns, and walls. (Large parking structure).

The odd thing is: Revit was only using about 30% of the CPU.

Can we boost Revit to use more?

[Anonymous]

One thing which i have found will slow down Revit incredibly, is having multiple views open that all display the change you are currently doing.

This may happen if you have multiple views placed on the same sheet, and you try to move a component which is displayed on all these views (even if the views are cropped to leave the component outside of the visible portion of the crop).

But it may also happen if you have multiple views open in seperate windows, especially if one or more of those are 3D Views - which could explain why you see a relatively light use of CPU power being used, as these are GPU heavy processes.

[ToanDN]

@kh_jea

Correct me if I am wrong but I think Revit does not use all the cores of your CPU unless you are doing a rendering.  So 30% sounds about the maximum if you have a 4-core processor (25% max out of 1 core and 5% from others for background tasks).  What about RAM utilization?  How many GB are you left with?

[scott_d_davis]

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@ToanDN wrote:

@kh_jea

Correct me if I am wrong but I think Revit does not use all the cores of your CPU unless you are doing a rendering.  So 30% sounds about the maximum if you have a 4-core processor (25% max out of 1 core and 5% from others for background tasks).  What about RAM utilization?  How many GB are you left with?

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Not true.  Revit is multi-threaded in many aspects.  Rendering is only one of these.

Here's a list of the tools/tasks that do take advantage of multiple processors/cores:

http://help.autodesk.com/view/rvt/2017/enu/?caas=caas%2Fsfdcarticles%2Fsfdcarticles%2FWhich-function...

[DarrenP]

yes it seems its more than just rendering now

here is the list: https://knowledge.autodesk.com/support/revit-lt/learn-explore/caas/sfdcarticles/sfdcarticles/Which-f...

[scott_d_davis]

There could be many things that could be causing performance issues.  My first concern is that you have a "simple" parking structure that the model is that large?  It also appears from your statement that you are maxing out your RAM.  Is 32 gigs of RAM in use?  If so, then you are now using the hard disk to supplement the memory.  Are your hard drives solid state drives?  If not, when you max out the RAM, HDDs will be slower than SSDs.  Get more RAM in these machines if you can.  And go with SSDs...

Another thing that can cause performance issues:

Warnings: How many warnings does the project have? Many warnings (generally anything above 500) can cause performance issues because every move you make, Revit wants to re-check your warnings.  Reduce your Warnings as much as possible.

[Viveka_CD · Accepted solution]

Hi @kh_jea

I recommend that you to keep the revit model speedy through best practices. (In addition to Audit, purge periodically atleast twice a week)

[kh_jea]

Well the structure itself is basic, the size isn't = 10.000 cars.

THe main issue I'm having with Revit being slow, is the fact that I have a 32 GB RAM, 3.50 GHz processer (Quadcore), and Revit doesn't seem to be using the PC to it's full potential. CPU is only at 30%, in other words Revit seems to only use one core.

What's the point of having a speedy PC if Revit only uses 1/4 of its potential.

[kh_jea]

I've managed to speed the model op a bit by deleting a bunch of Room Seperation Lines that where overlapping walls. There are a few gaps in the walls and instead of using the RSL for just the gaps, my colleagues decided to just redraw the complete boundary with RSL.

So yeah, that really slowed Revit down, as there where hundreds of warnings related to overlapping RSLL.

[Viveka_CD]

Hi @kh_jea

I'm glad to hear that you have managed to improve the speed the model!

Good that you started out deleting a bunch of Room Separation Lines that where overlapping walls. Sometimes we tend to overlook some of the warnings Revit produces. It is good practice to keep checking for warning atleast once a week. The most common are errors regarding rooms separation lines overlapping each other. 

Also we tend to create many views as the project progresses. 3D views, isometric views, sections, elevations slows down a model considerably - it is good to delete unused views and keep the ones which we really require. Also name your 3D views specifically and follow (Name them or get rid of them), same applies to tons of unused families. Finally remember to compact your file everyday.The compacting process rewrites the entire file and removes obsolete parts to save space. You can also consider a couple of 'save as' options to bring down the file size.Click HERE for more information.

Please mark this response as "Accept as Solution" if it answers your question to benefit other users looking for a similar solution. Kudos gladly accepted. 

[dgorsman]

It's not always possible to get things to work across multiple processors.  To do so, the steps taken have to be completely independent of each other.

One way to think of it is like the 4 x 100 Olympic relay race.  The first runner has to finish their leg before the second can get started.  And the second runner has to complete their leg before the next.  And so on.  In theory they could run at the same time in different lanes but the rules don't allow that.

Another way to look at it is with some basic math equations.  Lets say "A / (B + C)".  (B + C) has to be completed first before applying the divisor A.  The two steps cannot be done at the same time otherwise the results will be wrong.

Things like rendering and simulations can be done in parallel since the operations can be broken down into separate, independent blocks of data.

[VAdamskyi]

I like how every question about revit only using only 30% is dodged and the customer is blamed for overloading precious revit.

I have similar problem where I have ssd, 128 ram (currently most powerful designing laptop from Dell)

Yet, revit is lagging and only using 

I've complained to IT about it and they say that its not the computer but the revit issue.

He mentioned poor coding and poor optimization.

Never had an issue with other apps like: cad, solid works, inventor. 

Only happens with revit.

[HVAC-Novice]

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@VAdamskyi wrote:

I like how every question about revit only using only 30% is dodged and the customer is blamed for overloading precious revit.

I have similar problem where I have ssd, 128 ram (currently most powerful designing laptop from Dell)

Yet, revit is lagging and only using 

I've complained to IT about it and they say that its not the computer but the revit issue.

He mentioned poor coding and poor optimization.

Never had an issue with other apps like: cad, solid works, inventor. 

Only happens with revit.

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Fastest laptop from Dell is like saying you got the fastest 3-legged horse. What exact specs? And what are the temps? They overheat, and then the CPU/GPU throttles.

Open task manager and show all logical processors. You most likely see a single core (single thread) doing all the work on many Revit tasks. Out of 8 cores with HT a single core working 100% will only contribute to 6% of total CPU performance.  

And windows task manager doesn't show correct clock speed. You need to install Ryzen Master (AMD) or XTU (Intel) to see what each core is doing. Some cores will run at 5GHz, some will be sleeping. And monitor temperatures, especially on a laptop. 

Yes, Revit has some poor coding and is poor on multi-threading. But a CPU with high single-core speed still will leverage good hardware. and obviously there is also modeling efficiency. I recently got a new PC and it really got a few fold better. There isn't a laptop that can perform very well. 

And what version of Revit are you using? Since this is an old thread, i just say that modern Revit versions allegedly use more cores better than older versions (at least to every year's release notes....) 

Some forum member made a benchmark for Revit and you can see that modern hardware really helps. 

https://goto.archi/best-laptop-cpu-for-revit

[luisPDAN6]

Have a look at the free Hardware Benchmark app that is the Revit App store to check issues related with your hardware/system.

https://apps.autodesk.com/RVT/en/Detail/Index?id=5685208554472651007&appLang=en&os=Win64

You should be able to compare with other systems.

[RSomppi]

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@VAdamskyi wrote:

I like how every question about revit only using only 30% is dodged and the customer is blamed for overloading precious revit.

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I wouldn't say that is what is happening.

In order to prove that it is a programmatic issue, model issues need to be ruled out as they are quite common. Most of the "complaints" about the program that come up here are solved by addressing workflow and content issues. So, yeah, it is THE most common reason for poor model performance. It's amazing how much Revit can do but it HAS to be done correctly. Also, there are a lot of misconceptions about Revit out there.

[HVAC-Novice]

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@RSomppi wrote:

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@VAdamskyi wrote:

I like how every question about revit only using only 30% is dodged and the customer is blamed for overloading precious revit.

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I wouldn't say that is what is happening.

In order to prove that it is a programmatic issue, model issues need to be ruled out as they are quite common. Most of the "complaints" about the program that come up here are solved by addressing workflow and content issues. So, yeah, it is THE most common reason for poor model performance. It's amazing how much Revit can do but it HAS to be done correctly. Also, there are a lot of misconceptions about Revit out there.

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Revit has a few odd inefficiencies. My hardware (see signature) is pretty good. and my model is clean and usually works fine. But when I for example move the level head marker to left or right (which should take zero effort) i get the spinning wheel for 1-2 seconds. None of the threads goes up (I have task manager open all the time). This  clearly is a Revit issue since the CPU is just bored.  

For other activity (i.e. PDF creation) i can see Revit only uses a single thread at 100%. i have 8 P-cores with 16-threads and Revit literally only uses a single thread while I have to wait. 

Old hardware, and modeling play a role. But Revit also has some serious issues and the lack of leveraging multi-core CPUs is frustrating. 

Overall upgrading to my recent specs has greatly improved the very day use of Revit. So don't dismiss modern hardware. and you have to look into the task manager details and Ryzen Master or XTU before jumping to conclusions. But there are still some seemingly simple tasks Revit still is slow at. 

[RSomppi]

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@HVAC-Novice wrote:
But there are still some seemingly simple tasks Revit still is slow at. 

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Just take into consideration that not everyone experiences these issues. The hardware requirements are a given. I've worked on inadequate systems and the behavior is quite similar to what is being described in this thread. 

Your example with the Level Head is something that I can do all day long in larger models without issues.

There are also background processes that people are not aware of. Some seemingly "simple" tasks can have ramifications on what is happening behind the scenes.

Also, I don't think this is an appropriate place to discuss "programming" issues. Discussing how to optimize model performance would be much more appropriate but the complaints with people's opinions on programming belong elsewhere.