[ALEJANDRO]

   
I have noticed that none of the robot models in the RoboDK library match our KR 210 R3100-2 DH parameters. 
I have followed the instructions to model it ourself but we cannot find a way to save the robot itself as a .robot to a local library to be used in other stations

Also, It might be better to simplify the robot geometry further to ease the collision checking computation or, as it is done on the Gazebo simulator, add an additional fully simplified mesh just for collision checking

I am attaching my robot station for you to compare

[Sergei]

You can save your robot or mechanism by right-clicking on it and selecting the 'Save As...' command from the context menu:

   

Also, you can try using the Simplify Mesh Add-in to optimize the model size:
https://robodk.com/addin/com.robodk.app.simplifymesh