If solidworks is taking a long time to open a STEP file, first try opening from your local PC instead of from the network.
After that, try saving it as an assembly instead of as a STEP file.
If you only need to see part of it, use this
https://help.solidworks.com/2024/english/SolidWorks/sldworks/c_step_files.htm
https://www.reddit.com/r/SolidWorks/comments/18dj2sb/solidworks_assemblies_take_10_minutes_to_open/
Also,
The issue may be that the SolidWorks interconnect is not checked. If this is not checked, then open options, then import, and then check SolidWorks Interconnect. This should speed up the loading time. you will need to right-click on the assemblies and break the connections to open the part files