What is the best iMac choice for SketchUp 2020?

I apologize in advance if I’m posting this in the “wrong” category … please advise, I’m doing my best to navigate this form …

What is the Best iMac Choice for SketchUp 2020?

Being aware that SketchUp (still) utilizes only ONE processor of the now commonly available multi core chip configurations, I am contemplating an iMac upgrade. I have heard that the Video Graphics card “speed/capacity” is very important to SketchUp performance. I am committed to staying in the Apple universe, so one dilemma I face is that while the current iMac lineup offers slightly higher processor speeds, the iMac Pro offers slower processors (w/ more cores, which don’t help), but much bigger/faster Graphics Cards …

I need to figure out which is more important to the total SketchUp experience, processor speed or Graphics Card capacity/speed!

For a base line comparison, I am currently running SketchUp Pro 2018 on my iMac 27” Core i7 4.0 GHz (5K Late 2015) w/ 32 GB RAM and a Radeon R9 M395X w/ 4GB of GDDR5 memory.

Despite lean file sizes and best modeling practices/work flow, I still get the “spinny wheel” frequently while using Layout.

Processor Questions:

  1. Which is more important, the “base” speed of the processor or the “turbo boost” speed?

For instance, is 3.7 GHz w/ turbo to 4.6 GHz better than … 3.6 GHz w/ a turbo of 5.0 GHz?

  1. When and how is this turbo boost triggered? Does it run for a whole task/demand cycle, or is it strictly “temporary”?

Video Graphics Questions:

How much of a difference in SketchUp performance will there be between the following two Graphics Card options:

  1. Radeon Pro 580X w/ 8GB of GDDR5 memory. (Currently available iMac 27” 5K)

  2. Radeon Pro Vega 48 w/ 8GB of HBM2 memory. (Option, + $450, current iMac 27” 5K)

And, if the Video Graphics speed/capacity is really of paramount important to SketchUp performance, how dramatic would the following option be?

  1. Radeon Pro Vega 64 w/ 16GB of HBM2 memory. (Currently available iMac Pro 27” 5K, but it costs lots of extra $$).

Regarding the above iMac Pro 27” 5K option - the downside of this choice is that it’s paired with a maximum processor speed of only 3.3 GHz w/ a turbo to 4.2 GHz). So, trade offs?

The iMac Pro choice will also cost me about $3K more, so I really need to believe this processor/graphics choice is superior …

So, it appears that my choice is between a faster processor paired with only an 8GB video card (Currently available iMac 27” 5K), or a slower processor paired with a bigger/faster Video Card (Current iMac Pro 27” 5K).

Any help or advice on the various iMac upgrade choices to best run SketchUp would be most appreciated!

Thank You SketchUp Community

Honestly they will all run it just fine. The processors and video cards will handle normal sketchup work with ease. The Pro even more capable of course. I know we can get into particulars about the small differences in performance for each configuration but it seems like you’ve already done that thoroughly.

If you are really just interested in raw performance then maybe don’t even get an iMac at all. Maybe a powerful PC is a better solution for the money. And I’m a lifetime Mac guy myself.

If you’re not really rendering anything, just get a top spec iMac and add tons of RAM after market. If you plan to do serious production and/or video graphics and audio work the Pro MIGHT help. Otherwise it’s not worth it.

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Thanks for your input … it helps, but I’m still looking for some guidance on which is more important, chip processor speed, or graphics processor speed … I suppose the answer may be, yes - both!

A little of both for sure. They work together to calculate geometry and then draw it. Can’t ignore one in favor of the other. That being said sketchup doesn’t require a powerful graphics card.

OK, thanks again for your words, maybe that says it all.
And yes, I get it that the Windows PC environment would give me a few more options …
I was just hoping for some news that some combination of processor and graphics could finally overcome the really sluggish performance of Layout … I really appreciate what Layout CAN do, it just does it SO slowly!
I’m frustrated that my productivity would be so much better if Layout could just be as fast a SketchUp, and since I can’t solve the Software problem (and Trimble doesn’t seem to want to either), I was hoping that the Hardware could help, at least a little bit!
(I know there are lots of well worn threads on Layout performance issues elsewhere in the Form).

Just a general observation: If you are now running SketchUp/LayOut on a not very old system (with a decent i5/i7 processor and a dedicated graphics card) you will probably not be satisfied with the results of any hardware upgrade, however expensive. As 3D modellers are single-threaded, all data must squeeze itself through that, so the amount of faces and edges to be processed is critical. So when looking for a processor for SU, single thread performance is the most important factor. But in a recent thread there was a forum member who had a processor quite from the top of the performance chart, and a similarly “ultracool whizbang” graphics card, and he was disappointed about the performance.


Hi @beamer

Your original question is exactly the same as the query I have, so I’m glad you asked it.

I currently have an iMac i7 4.2GHz with 40GB RAM, 4GB GPU, as well as an External Vega 64 Pro 8GB External GPU, which is used for Rendering.

I too am looking at the iMac Pro. I’m thinking that although the processor is only 3.3GHz, it will be faster because it’s a Xeon, so better than an i9?

While Sketchup runs extremely well, Layout is the major issue, and runs so poorly compared with Sketchup. Layout actually runs better on my older MacBook Pro with a far less superior spec, and no dedicated Graphics Card.

So, I really wish Trimble would sort the issue with Layout. It’s like running a 100m race and winning with Sketchup to then be bogged down in Treacle for the Lap of Honour with Layout.


Hi @Anssi

For me the Sketchup performance is irrelevant as it runs faultlessly on the iMac and really fast and smooth.

It’s Layout that is the major problem. Why does Layout not run as smooth and as quick as SketchUp?


Thank you Mike,
I understand that you are running an i7 4.2 GHZ, which is slightly better than my 7.0, but otherwise, as far as I can tell from your comments, we are enduring about the same 4GB graphics card.
I’m still waiting for a definitive opinion on how one particular processor’s “GHz rating” is better than another, does the specific “type of processor” (Xeon, for instance) make any difference in the evaluation I posed in my original post?

Thanks again Mike,
I obviously agree that the SPEED of the LayOut software is the bane of our collective user experience!

Trimble - If you are reading this - please wake up! Make Layout a robust 2D program, instead of the hobbled cousin we all have to placate, suffer, and humor!

Hey Mike,
I just noticed another comment from your earlier post …
Did you actually state that you have somehow connected an “external” Vega 64 Pro 8GB Graphics card/processor to your iMac? I had no idea it was possible to run an external graphics processor on an iMac. I’m interested - how is this done? If this is possible, it could be a huge answer to some of my problems …
Please advise …

Layout performance wont be boosted much…minor incremental performance only, nothing like double the speed… I was planning to run some tests looking at Video Memory (ram) and the effect on LO performance but havent gotten arpund to it yet.

LO performance relies on working on small models, small documents (several files as needed) and both SU model and LO files on your local SSD hard drive…and dont use vector or hybrid mode on anything complex.

GHz ratings are only directly comparable between CPUs of the same series, eg intel 8th gen (i7 8100, 8500, 8600, 8700k). Each newer series usually boosts system performance (not necessaryily SketchUp performance) by about 5%, so a 8700k might be 5% faster than a 7700k.

xeon labelled cpus are not noticebly faster than core i7, . but they are built mainly for servers and reliability, hence higher prices.


Mmmm, kind of defeats the purpose then when using Layout as a Professiinal Business for Professional Organisations producing documentation for Construction.

This I why I do believe that ALL effort by Trimble should be put into improving Layout, even if it means deleting ALL the code and starting from scratch. SketchUp is fine. Leave SketchUp alone, (apart from minor Bug fixing). It’s ridiculous that I can work on an 1GB plus size image in Photoshop, performing professional retouching for magazine images, with multiple layers, with absolutely NO issues, and yet a 5MB Layout file performs so slow.

Surely this indicates something is wrong.



Hi @beamer

Yes, the External GPU is mounted in a Razer Core X case and plugs in to a Thinderbolt port.

I bought this for use with Twinmotion for rendering. In Mojave and Catalina, it is possible to tell the software to use a specific GPU, so I have told Twinmotion to use the External GPU.

Unfortunately, I don’t think it is possible to tell Layout to use this GPU.

As mentioned in another reply, this is why I think that Layout needs to be rewritten from scratch.

As a side note, when I bought my current iMac it only came with 8GB RAM as I decided I would buy the additional RAM as it’s cheaper than asking Apple to increase the RAM. With only 8GB RAM I was shocked at how bad Layout was. It was actually unusable. When I increased to 40GB there was a huge performance difference for Layout. Still slow but at least usable. Therefore, I think RAM has a big effect.


Have to agree with @MichaelSiggers. Vector or Raster is entirely impractical for construction documentation with any sort of detail.
Just have to accept that Layout is slow, regardless of of hardware specs once you reach certain spec level, SU speed is fine.



I’ve still no understanding why Layout ran better on my older, less specced MacBook Pro under High Sierra, compared with a much much higher spec iMac using Mojave and now Catalina.

Both are now on Catalina. SketchUp: Usain Bolt running the 100. Layout: Me running the 100! :grinning:


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I would consider this option as well…


Thanks Sam, this is useful information, avoiding vector & hybrid modes is all ready part of my best practices, as is only one page per Layout file … Sounds like there is definitely some diminishing return in faster hardware investment!

Thanks John, I have a second 28" 4K monitor now … I hadn’t really thought about using a second iMac as another “engine” in addition to a 5K monitor … Maybe if and when I get into more heavy rendering …

Hey Sam, if you ever do get around to testing LO against amount of Video Memory, I will be most interested in your conclusions … As I mentioned in my original post, I’ve only got 4GB now, am contemplating what I have to do to get up to the 8GB level, and then there’s the really expensive jump to 16GB.
By the way, do you happen to know if these Radeon video cards are “user” upgradeable in iMac’s? Are they “hard soldered” to the mother boards, or ? Do these different levels of Video ram on the cards have the same “plugs” or sockets, or is each one different, and thus not “upgradable”?
Then, I suppose there is the thermal cooling issue … (I suppose it would void the warrantee too, but then mines’ almost over anyway!).