Are you editing the smart objects or using replace content. What kind of objects are you using. All smart objects are not created equal. place Jpeg would not Support 16Bit Color. A place png object when edited the saving of the work document may take some time. Saving a png file seems to take a long time one my windows PC. I avoid using Start Object layers in Mockup templates that has Objects the are RAW files, Vector File, Png Files and Jpeg File. For various reasons. RAW files will open in ACR, Vector Files open in AI. If a script populating templates my script would loose control for theose object types. Jpepg for editing you need the remember to flatten for Save will not work if you add layers save will switch to Save AS and the work document backing file would not be overwritten, The smart object layer would not be updated. Png for savings Png take a long time and transparent borders may be trimmed,
I just use depth channel/image form Blender exrs inside smart objects. The only reason I need 16 bit in a document . Save it as psd linked of embedded , no differnce . It takes a bit less time with compression off but still a slow tourture to work with nevertherless. So any adjustment tweak I do inside smart object it takes forever first to save embedded psd and then foreve again to update master document. Same thing in Afinity Photo for example takes no time at all. Well, you don't even have to save "smart objects" there.
So I hoped maybe I am missing something. Some hidden checkbox in setting, quicker SSD for cache files or something?