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

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kh_jea
7407 Aufrufe, 12 Antworten

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

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?

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Nachricht 2 von 13
Anonymous
als Antwort auf: kh_jea

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.

Nachricht 3 von 13
kh_jea
als Antwort auf: Anonymous

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?

Nachricht 4 von 13
Anonymous
als Antwort auf: kh_jea

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.

 

Nachricht 5 von 13
ToanDN
als Antwort auf: kh_jea

@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?

Nachricht 6 von 13
scott_d_davis
als Antwort auf: ToanDN


@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?


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...



Scott D Davis
Sr AEC Technical Specialist
Nachricht 7 von 13
DarrenP
als Antwort auf: scott_d_davis

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...

DarrenP
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Nachricht 8 von 13
scott_d_davis
als Antwort auf: kh_jea

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.

 



Scott D Davis
Sr AEC Technical Specialist
Nachricht 9 von 13
Viveka_CD
als Antwort auf: kh_jea

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)

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Nachricht 10 von 13
kh_jea
als Antwort auf: scott_d_davis

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.

Nachricht 11 von 13
kh_jea
als Antwort auf: Viveka_CD

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.

Nachricht 12 von 13
Viveka_CD
als Antwort auf: kh_jea

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. 

Nachricht 13 von 13
dgorsman
als Antwort auf: kh_jea

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.

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