Complexity of imported obj files

Hi everyone, I´d like to know if there´s a simple way to make imported files less complex.

Here´s the problem: I am using the ESKO Studio Plugin for Adobe Illustrator to export "folded" objekts like displays made of cardboard as an .U3D file to open these in Photoshop. Then I export my 3D layer as an .OBJ File in order to open/import this file in Adobe Dimension. The pitty is, that already my 3D layer in PS has so many seperate texture files included, that the final work in Dimension gets really slow, especially when I duplicate these objects. I often have to save my work in order not to crash the application and sometimes, when I try to re-open saved files, I get an error message that something went wrong and dimension wont work properly. Even after restarts of the app and the system some of the .dn files can´t be opened again. Using DN 3.3 on mac high sierra/mojave. Any tips to "flatten/merge" all these textures already in PS to make this process less complex? I already try to generate UVs in PS, but this does not really help und the exported 3D layer as an .OBJ has a much bigger file size, too. Anybody else having experience with generating less complex .OBJ files. Maybe even a tip with exporting the original 3D file out of Illustrator with the ESKO plugin. Thanks in advance for response and/or help. 

Greets from Germany