Photoshop slow when working with smart objects

You could try linking the larger images instead of embedding. I'm not sure how that would work if they're smart objects you created within the file or separate images. Though, it really helped me. It would cause an issue should you move the linked files of course.

I experience similar issues as well, I use a machine with 32GB of RAM, Separate drives for temp files and project files, SSD and non SSD don't seem to change anything, Large and small files alike.  The only thing I seem to be able to do to stop it from stalling out on a regular basis, is forcing it to open a small file of any kind, suddenly the transform or whatever I'm trying to do happens almost instantly and then it goes to the other file. This began with CC2019 and I did not have the problem with CC2018 or CC2017 but I can no longer install those versions.

As a result now, I just have to keep opening a super small photoshop file every time it starts lagging out (which is very often).  I'm so glad I finally found someone else having this issue, it's been driving me nuts. forcing a file to open however, somehow makes it all happen magically when if I don't open the file, it can take several minutes sometimes to finish whatever is happening.

Hey there, yes something is up with the more recent versions of Photoshop CC, or you are hitting the roof of the capabilities. What has happened to me with recent updates and was previously not a problem, is a file that has around 70 layers in it of 60px icons for a website that I use to drop in and colour etc, has been fine fine fine adding to it and it has grown over time then adding in one layer now and Photoshop just grinds to a complete halt, it's only using 10% CPU, has 30+ GB of Ram available, is using a GTX1060 + 8700K i7 3.70GHz machine, it's fast and does most everything instantly - NVME scratch disk and lots of ram applied to it too. Windows obviously - but I feel I have reached the cap of the ability of Photoshop to handle smart objects at around the 60 mark, not all layers are smart objects, I have had to break the one file up to three groups of 25 layers now so I can work on it. Even the mouse skips and jumps when I am going over the page, but I can swap out to any other app and it's working fine, ram usage is 2GB and CPU no more than 10 at peak, go back to photoshop and nothing changes but the computer just seems to lag like it's maxed out in every respect. Mouse lags, stops, clicks take a minute to register, then happen all at once etc. It's horrendous. So I would say we both have pushed things beyond Photoshops capabilities. It needs to be fixed.

There are so many variables involved in this. 
You mentioned having multiple documents open, and you could also have multiple applications open, you might not have the recommended 8GB of RAM, you might not have much hard disk space, your computer is old so might be running slowly, and the smart objects could be huge bitmaps, and smart objects retain the actual file size so the files could be really large. Lots of different factors here.

Hi there,

We apologize for the performance issues you are facing while working with smart objects in Photoshop.

Would you mind sharing the version of Photoshop you are currently using by going to the Help menu > System info? Also, approximately how many smart objects do you have in the document?

You can try to optimize the preferences of Photoshop using the steps mentioned in the link below.

https://helpx.adobe.com/in/photoshop/kb/optimize-photoshop-cc-performance.html

If optimizing the preferences does not help, you can also try to reset the preferences using the steps in the link below.

https://helpx.adobe.com/in/photoshop/using/preferences.html

Regards,

Nikunj

It seems that this is a file issue not the software if you aren't experiencing it across the board.

What are the file specifics? Size (MB/GB), Image size, layers, etc.