If the software fails to load large published documents, make sure the SmartPlant Foundation file service, 3D compression, and general execution timeout settings have been set correctly. These are described in Configure the server for hosting installed software. You can also modify the client file service timeout setting, as described in File transfer from the client to file service exceeds timeout. Ensure that the web application pools are set up correctly, as documented in Set up IIS Application Pools and User Accounts Manually.
Loading large files uses a lot of memory. Ensure that the server hardware matches the recommendations documented in SmartPlant Foundation Hardware and Software Recommendations.